Re: [MBZ] 124 AC woe
Probably not the solution you desire, but I found out you can use coil cleaning spray product to dislodge the built up snot on the condenser and it does increase the cooling effect. I gave it a shot on my S430 and what was once blackened became silvery once more. The warm weather had been taxing the cooling for both AC and engine, and now the gauge does not climb much beyond 100 at idle. Vent temps are cold. Not ice, but cold clay On Jul 12, 2014, at 4:47 PM, Meade Dillon wrote: Today I've re-charged the AC in my '95 E300 Diesel in order to have some decent cooling for the rest of the season. I added about 2 oz of PAG46 compressor oil and about 12 oz of R-134, and the pressure gauges didn't quite show a full charge (21 Bar on the high side, a little of 2 bar on the low side, at about 25 deg C ambient). The vent temperature was really nice, it would pull down to 0 deg F. I had a lot of trouble with the serpentine belt slipping, tried cleaning the cheapo Gates belt (from Napa a while back), tried an old belt from my wagon (too big, also slipped), finally I mounted the brand new Conti belt I had in the correct size, which I'd been saving to use after I re-seal or replace the leaking power steering pump. The pump is not leaking now, I've let the hydraulic fluid reservoir for the ASD get low. So finally I put on the new belt, I was very happy with the vent temperatures, but then the compressor started cutting out for no apparent reason. The belt was not slipping that I could detect. Took a test drive, while on the road with no stop/start, the compressor seems to run fine and then cut out. I suspect the evaporator temperature is getting too cold, so the PBU is shutting off the compressor. If I shut off the car and restart, the compressor will engage again. Anyone have a suggestion? Thanks, Max ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
Ok, after further investigation, I think the new serpentine belt is also slipping. This Conti belt just makes a lot less noise when it slips. I think I need a new belt tensioner spring. May try cleaning off the new belt and pulleys first. Correction on the vent temperature, 40 deg F is probably closer to the actual temperature. I was using my non-contact thermometer, and pointing it directly into the vent, and I think the cold air blowing right into the sensor was throwing it off. Max Dillon, Charleston SC ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
I forget, is this a diesel or a gasser? Gasser belt tensioners have to be replaced quite often. Diesels, which have a vastly better tensioner system, only once or twice a decade will the spring break. Have had a few shocks go bad and knock, but the belt doesn't slip. Peter ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
Thanks all! I think Peter has given me a good place to start trouble shooting. Reading the HVAC manual about the evaporator temperature sensor, there is this note: On vehicles as of 09/87, the refrigerant compressor is switched off by the control unit after 2 minutes of operation if there is a short circuit in the temperature sensor evaporator (resistance value below 2.5 kOhm). This prevents continuous refrigerant compressor operation and subsequent icing-up of the evaporator. The refrigerant compressor is only switched on again after the engine has been switched off and on again. So I shall attempt to test the evap temp sensor and the expansion valve. No dry ice here. I do have a can of air, can turn that upside down and get some pretty cold spray. Hmmm... -Max On Sat, Jul 12, 2014 at 10:29 PM, Peter Frederick psf...@earthlink.net wrote: W124 has a thermistor just in behind the evaporator that senses the temp. Will cycle the compressor to prevent freeze-up. However, if the expansion valve is bad, it will seriously overcool, and then the computer will not turn the compressor back on until the evaporator thaws out, which takes a while with no airflow. The temperature of the return line to the compressor should be 35 to 38F, whatever pressure that is on an R134a system. You can test the expansion valve with some very cold ice (dry ice works best, but it's hard to find and dangerous. Use a cube straight from the freezer). With the system up and going, put the ice on the bellows of the expansion valve (the do-dad on top). This should close the expansion valve and drop the pressure in the return line to near vaccum (which is why dry ice works better, it's way to cold -- ice won't go below 32F and you need it colder). If it doesn't drop, the expansion valve is stuck open and it will seriously over-cool the evaporator. Peter ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
Evaporator temp sensor is above the accelerator pedal on the side of the heater box. Peter ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
The vent temperature was really nice, it would pull down to 0 deg F. Way too cold, no matter how nice you might like it to be there. Things'll ice up. I saw such temps once on the Ebola Fishtank, when the filter screen at the expansion valve was gunked up. (This is unlikely to be your particular problem, the system in a 250C is unlike yours.) -- Jim ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
On Sat, 12 Jul 2014 19:47:06 -0400 Meade Dillon dillonm...@gmail.com wrote: Anyone have a suggestion? Wait for a hotter day? Don't run the temperature dial so low? Change the resistor that determines how cold things can get? Craig ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
It should not be dropping down to 0, I would think more in the upper 30s would be what temp it should run at the vents Sent from my iPhone On Jul 12, 2014, at 6:47 PM, Meade Dillon dillonm...@gmail.com wrote: Today I've re-charged the AC in my '95 E300 Diesel in order to have some decent cooling for the rest of the season. I added about 2 oz of PAG46 compressor oil and about 12 oz of R-134, and the pressure gauges didn't quite show a full charge (21 Bar on the high side, a little of 2 bar on the low side, at about 25 deg C ambient). The vent temperature was really nice, it would pull down to 0 deg F. I had a lot of trouble with the serpentine belt slipping, tried cleaning the cheapo Gates belt (from Napa a while back), tried an old belt from my wagon (too big, also slipped), finally I mounted the brand new Conti belt I had in the correct size, which I'd been saving to use after I re-seal or replace the leaking power steering pump. The pump is not leaking now, I've let the hydraulic fluid reservoir for the ASD get low. So finally I put on the new belt, I was very happy with the vent temperatures, but then the compressor started cutting out for no apparent reason. The belt was not slipping that I could detect. Took a test drive, while on the road with no stop/start, the compressor seems to run fine and then cut out. I suspect the evaporator temperature is getting too cold, so the PBU is shutting off the compressor. If I shut off the car and restart, the compressor will engage again. Anyone have a suggestion? Thanks, Max ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
Yeah, that's way too cold. If the evaporator is freezing up, which it almost has to be to get duct outlet temps at 0F, the low temperature switch/sensor would be making the compressor cut out. One trick I used to do on W126 cars was to remove the low temperature switch and recalibrate it to about 35F to get the lowest possible evaporator temperatures without freezing it up. Stock from the factory they usually opened up around 40F. That extra 5 degrees would make a difference in this climate. Dan On Jul 12, 2014, at 9:09 PM, Kaleb C. Striplin ka...@striplin.net wrote: It should not be dropping down to 0, I would think more in the upper 30s would be what temp it should run at the vents Sent from my iPhone On Jul 12, 2014, at 6:47 PM, Meade Dillon dillonm...@gmail.com wrote: Today I've re-charged the AC in my '95 E300 Diesel in order to have some decent cooling for the rest of the season. I added about 2 oz of PAG46 compressor oil and about 12 oz of R-134, and the pressure gauges didn't quite show a full charge (21 Bar on the high side, a little of 2 bar on the low side, at about 25 deg C ambient). The vent temperature was really nice, it would pull down to 0 deg F. I had a lot of trouble with the serpentine belt slipping, tried cleaning the cheapo Gates belt (from Napa a while back), tried an old belt from my wagon (too big, also slipped), finally I mounted the brand new Conti belt I had in the correct size, which I'd been saving to use after I re-seal or replace the leaking power steering pump. The pump is not leaking now, I've let the hydraulic fluid reservoir for the ASD get low. So finally I put on the new belt, I was very happy with the vent temperatures, but then the compressor started cutting out for no apparent reason. The belt was not slipping that I could detect. Took a test drive, while on the road with no stop/start, the compressor seems to run fine and then cut out. I suspect the evaporator temperature is getting too cold, so the PBU is shutting off the compressor. If I shut off the car and restart, the compressor will engage again. Anyone have a suggestion? Thanks, Max ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
I believe it's the same setup on a W124 - a capillary tube that is inserted into the evaporator fins from outside the box, with a mechanical switch that opens and closes based on the temperature of the capillary bulb? https://www.dropbox.com/s/ef3nr80azddqyhs/MVC-016S.jpg https://www.dropbox.com/s/x3wb7k4f82l9fe3/MVC-019S.jpg This is what it looks like on a W123. Dan On Jul 12, 2014, at 9:14 PM, Dan Penoff d...@penoff.com wrote: Yeah, that's way too cold. If the evaporator is freezing up, which it almost has to be to get duct outlet temps at 0F, the low temperature switch/sensor would be making the compressor cut out. One trick I used to do on W126 cars was to remove the low temperature switch and recalibrate it to about 35F to get the lowest possible evaporator temperatures without freezing it up. Stock from the factory they usually opened up around 40F. That extra 5 degrees would make a difference in this climate. Dan On Jul 12, 2014, at 9:09 PM, Kaleb C. Striplin ka...@striplin.net wrote: It should not be dropping down to 0, I would think more in the upper 30s would be what temp it should run at the vents Sent from my iPhone On Jul 12, 2014, at 6:47 PM, Meade Dillon dillonm...@gmail.com wrote: Today I've re-charged the AC in my '95 E300 Diesel in order to have some decent cooling for the rest of the season. I added about 2 oz of PAG46 compressor oil and about 12 oz of R-134, and the pressure gauges didn't quite show a full charge (21 Bar on the high side, a little of 2 bar on the low side, at about 25 deg C ambient). The vent temperature was really nice, it would pull down to 0 deg F. I had a lot of trouble with the serpentine belt slipping, tried cleaning the cheapo Gates belt (from Napa a while back), tried an old belt from my wagon (too big, also slipped), finally I mounted the brand new Conti belt I had in the correct size, which I'd been saving to use after I re-seal or replace the leaking power steering pump. The pump is not leaking now, I've let the hydraulic fluid reservoir for the ASD get low. So finally I put on the new belt, I was very happy with the vent temperatures, but then the compressor started cutting out for no apparent reason. The belt was not slipping that I could detect. Took a test drive, while on the road with no stop/start, the compressor seems to run fine and then cut out. I suspect the evaporator temperature is getting too cold, so the PBU is shutting off the compressor. If I shut off the car and restart, the compressor will engage again. Anyone have a suggestion? Thanks, Max ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
W124 has a thermistor just in behind the evaporator that senses the temp. Will cycle the compressor to prevent freeze-up. However, if the expansion valve is bad, it will seriously overcool, and then the computer will not turn the compressor back on until the evaporator thaws out, which takes a while with no airflow. The temperature of the return line to the compressor should be 35 to 38F, whatever pressure that is on an R134a system. You can test the expansion valve with some very cold ice (dry ice works best, but it's hard to find and dangerous. Use a cube straight from the freezer). With the system up and going, put the ice on the bellows of the expansion valve (the do-dad on top). This should close the expansion valve and drop the pressure in the return line to near vaccum (which is why dry ice works better, it's way to cold -- ice won't go below 32F and you need it colder). If it doesn't drop, the expansion valve is stuck open and it will seriously over-cool the evaporator. Peter ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com All posts are the result of individual contributors and as such, those individuals are responsible for the content of the post. The list owner has no control over the content of the messages of each contributor.
Re: [MBZ] 124 AC woe
Max Dillon wrote: Anyone have any advice? Do I simply need to be more patient about letting the r134 bleed into the system? If the can has frost on it, it won't be able to supply freon to a system that's programmed NOT to frost the evaporator side of the system. Either wait for the can to warm up, or stick it in a bucket of warm water. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 124 AC woe
You need some warm water to force the freon in -- partially immerse the can, it will boil and the gas will then go into the system. You have a frozen evaporator from low freon, that's why the pressure is so low on the low side (expansion valve is completely closed). You may also have water freezing out at the expansion valve, blocking it. More to the point, you need to find and fix the leak -- if the freon is slowly leaking out, air and water are leaking in. Heat, water, oxygen, and R134a make hydrofluoric acid, which will very rapidly eat the compressor. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 124 AC woe
Thanks Mitch, I can find some way to warm the can, but the hose is probably too short for a bucket of warm water to work. -Max (with cheap gauge and cheap hose) -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Mitch Haley Sent: Monday, February 21, 2011 7:09 PM To: Mercedes Discussion List Subject: Re: [MBZ] 124 AC woe Max Dillon wrote: Anyone have any advice? Do I simply need to be more patient about letting the r134 bleed into the system? If the can has frost on it, it won't be able to supply freon to a system that's programmed NOT to frost the evaporator side of the system. Either wait for the can to warm up, or stick it in a bucket of warm water. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] 124 AC woe
Thanks Peter. I'm trying to add r134 with UV dye so that I can find any leak present. I hope no water is in the system. Compressor seems to be fine. -Max -Original Message- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Peter Frederick Sent: Monday, February 21, 2011 7:09 PM To: Mercedes Discussion List Subject: Re: [MBZ] 124 AC woe You need some warm water to force the freon in -- partially immerse the can, it will boil and the gas will then go into the system. You have a frozen evaporator from low freon, that's why the pressure is so low on the low side (expansion valve is completely closed). You may also have water freezing out at the expansion valve, blocking it. More to the point, you need to find and fix the leak -- if the freon is slowly leaking out, air and water are leaking in. Heat, water, oxygen, and R134a make hydrofluoric acid, which will very rapidly eat the compressor. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
