No A/C

[8899]

I realize this problem has been discussed a fair amount in other threads but I was not able to identify similar circumstances.

Yesterday the upholstery shop completed the R&R of my GAT seat covers, which look and feel great btw. Instead of using steam to flatten and form the leather to the seat pads, the upholsterer prefers to let the car run for several hours with the heater on full (high temp and blower fan on high as well) with the windows closed. The cabin gets very hot allowing the leather to form to the pads.

When I picked the car up last night the cabin was still very hot. As I drove off in the rain (110% humidity with temps right around 78*F) trying to enjoy my leather seats I rolled the temperature switch to cold and and had the fan on high-speed. All I got was heat for the entire, miserable drive home.

This morning I drove the car into the office and continued to get no A/C. The temperature of the air coming out of the vents was similar to the outside ambient air temperature, similar to running the HVAC with the EC button selected.

Any ideas what happened and how I can get my A/C to work?

 

[Melville]

Sorry to hear about your AC issues. Could it be a blown fuse?

 

[nocfn]

Mono valve

 

[gerryvz]

It may well be your mono-valve, indeed. There is a thread on mono-valve replacement and testing. It's documented in the factory service manual.

Note that the mono-valve and aux coolant pump are separate units as installed on all E500E cars, similar to early-style (pre-1992) W124 models. Later W124s (except the V-8 models) used the integrated monovalve+aux pump module. The separate components on the E500E are located just ahead of the CAN box and also to the side and sort of behind it - a bit difficult to reach.

Cheers,
Gerry

 

[gsxr]

Make sure the AC compressor is running. If not, you need to find out why.

 

[maw1124]

Make sure the AC compressor is running. If not, you need to find out why.

Complete stab in the dark here, but if the AC compressor is known to be in good nick, but is not cycling on, you might look at the evap temp sensor.

http://www.500eboard.com/forums/showthread.php?t=7280 -- See posts #14, #27 and #28.

Good luck. Cheers,

maw

 

[8899]

Thanks guys. I emailed this thread onto my tech and he agreed with all of your suggestions. Now just need to get the car over to the shop...

 

[alabbasi]

Go back to basics. Turn A/C on and see if compressor is engaging. If not, put gauges on and check pressures. Could be either electrical or no a/c or as others suggested, mono valve.

 

[8899]

Closing this out. Failed A/C pressure switch shown in photo, and photos of new Behr switch to be installed.

http://www.autohausaz.com/pn/1248208310

 

[AndyK]

Hi there. Mine 1993 400e has similar issue. Intermittent absolutely unpredictable A/C cut off
I downloaded wiring diagram and it looks like the A/C compressor is directly controlled by the control module
Is that true or I have Klima relay same as 1994?
Previous owner already bypassed that sensor shown on pics above

 

[gsxr]

The 034/036 chassis do not have a KLIMA relay. This function is integrated into the GM/BM (General Module / Basic Module) in the CAN box. Check for fault codes on the BM/GM.

 

[AndyK]

The 034/036 chassis do not have a KLIMA relay. This function is integrated into the GM/BM (General Module / Basic Module) in the CAN box. Check for fault codes on the BM/GM.

That module has been replaced already, I borrowed it from 500SL
Nothing changed

 

[gerryvz]

You should really use a V-8 W124 specific BM/GM (400E420 or E500E, specifically).

 

[AndyK]

Even if part# matching ?

 

[gerryvz]

If the part number is the same, then it should be fine. The comprehensive list of part numbers used for our cars is found in the Wiki, located here:

https://www.500eboard.co/forums/wiki/?title=500E-and-E500-CAN-Computer-Part-Number-Reference

 

[AndyK]

If the part number is the same, then it should be fine. The comprehensive list of part numbers used for our cars is found in the Wiki, located here:

https://www.500eboard.co/forums/wiki/?title=500E-and-E500-CAN-Computer-Part-Number-Reference

Mine swapped to 5.0.
All the necessary modules are migrated as well.
So there might be differences…

 

[doolar]

Hi there. Mine 1993 400e has similar issue. Intermittent absolutely unpredictable A/C cut off
I downloaded wiring diagram and it looks like the A/C compressor is directly controlled by the control module
Is that true or I have Klima relay same as 1994?
Previous owner already bypassed that sensor shown on pics above

Have you checked the that you have the correct amount of refrigerant in the system? If the system lacks a few grams to many the system can be erratic until the gas weight drops low enough to not allow the system to engage at all, but that can take a while. The perceived weight and pressure can vary with for example temperature, making the fault intermittent.

And any stored codes would perhaps help too.

 

[AndyK]

Have you checked the that you have the correct amount of refrigerant in the system? If the system lacks a few grams to many the system can be erratic until the gas weight drops low enough to not allow the system to engage at all, but that can take a while. The perceived weight and pressure can vary with for example temperature, making the fault intermittent.

And any stored codes would perhaps help too.

yes I did, it's recently recharged ( I have A/C machine)

 

[gsxr]

And any stored codes would perhaps help too.

You haven't answered the question if you checked the fault codes stored on the BM/GM. If you don't have a blink code reader, you need to get one, immediately. Can't diagnose these cars without one.