a/c all of a sudden hot air
 

I was hoping not to add to the growing list of a/c issues on this board.

On Sunday the CE was cooling the car great on a 90 degree day.

Today my wife tells me no A/C...in fact it is just blowing hot air.

I guess the compressor isn't coming on.

I've done the dutiful search...but now seem confused on what the issues might be...

I have a spare Klima...but that's about my knowledge of A/C systems.

At least it's going to be cooler for the next couple of days until i can check things out....

i'll start with pressures, then klima...i'll look at the belt but I don't think that is an issue... any other ideas would be helpful.

Are your fans working properly...?
 

When it is too hot outside, if your fans are not working properly, that may be too taxing on an already weak 124 a/c system...
There are a lot of issues with the MB's a/c system. You can also look at the DIY articles on top of this page...There is an excellent article by Steve Brotherton. Here is the link:
http://www.peachparts.com/Wikka/AcDiags

Good luck!

I went thru a similar experience last summer.

If your low/high side pressures check out, you may have a blend door issue - too much outside air blending with the cooled down a/c air.

Could be something as simple as the fuse controlling the heater water vlaves being blown. Because the valves default position is open, you get hot air when the fuse blows.

Ok...i have started the trouble process on the 300CE

The compressor is not engaging.

I switched out Klimas...no change.

With the engine running ...low side pressure is 100..but no compressor engaging.Last year some leaking o-rings around the expansion valve were replaced.

Sunday the A/C seemed to be working fine in 90 degree weather..maybe it could have been a bit cooler. However it was very comfortable driving.


I checked my son's 300e. Low side pressure is at 25 or so with A/C on high
His low side is at 80 with compressor off and engine running

Both cars were converted 134a.(at least by the size of the fittings)..not by my choice..that's the way they were purchased.

I really can't get anywhere with the CE until the compressor engages... the clutch turns freely by hand.

Thanks for any more ideas.

The only other unusual thing is that the car sometimes has the gurgle issue when the A/C is on and working. However, i can't seem to detect any coolant issues.


EDIT -- 8:37 pm it is dark... i'll check the ovp fuse tomorrow..but the car is running perfect otherwise. Since i have the 300e... any suggestions on switching out parts helps me..

You can jump the connections from the low pressure cutoff switch on the reciever/dryer and see if the compressor runs. Just connect for a second to see if it causes the clutch to engage and starts running. If that happens maybe you are just low on freon.

If it is low you might want to add dye and freon and see how long it lasts. If it only lasts a week or two you may have a good size leak that you'll need to locate.

Ron,
Sounds right to me but, is the pressure on the low side supposed to be that high? Maybe the receiver dryer or tx valve is shagged.

well this morning it blew the cliamte control fuse.... i believe it's number 7 in the box..red fuse.

maybe that's a good sign that this is a pesky electrical problem rather than an expensive mechanical one...

10:10 pm, Friday night EDIT

hot air is being forced through the heater vents when the car is moving.... blower is off (fuse blown) if you adjust the temp wheel it's still hot air... hot like heated air....