Help.... 100+ degree index here in Charleston, A/C issue
 

Hello good people, here I am again asking for help from the Benz lovers.

I have a 1988 300 SE.

Recently I have been having a few issues with it, this is the latest one, my Air conditioner.
When I get in the car, the A/C is cold.
If I travel for about 30 mins, it quit cooling.

I can pull over the side of the road, cut the engine off and restart, the A/C will resume cooling or another 20 to 30 mins, I am lost.

I pulled the relay and opened (Klima) nothing seems to be out of the ordinary.
Sometimes when it rains, the same issue happens.
At first I thought that water was getting under the hood of the car, but non-to that effect.

Can someone help me?

More Information..
 

I have stopped on several occasions to see what is going on under the hood while the engine is running. The clutch was disengaged on the AC unit. I checked the high-pressure switch, the wiring to the switches and the connections to the AC unit it self, I even thought that it may have been the high speed switch. But it happens at all speeds and there seems not to be anything wrong with the connections and all. I have removed the AC relay and replaced it while the car was running, after a few seconds it started. I still don’t think it was the relay, but I do have one on order. I just checked the temp sensor in the car and it seems to be fine as well. I did discover something, I put some gauges on the system and it seems as if the low side is running a higher pressure than it should. I have started to lower the low side to about 30 pounds. The high side is fine at around 245. Tomorrow I will replace the dryer and vacuum the system for a couple of hours, starting over. Still searching and looking for more advice. The next time it shuts down I will disconnect the mono valve and see what happens. If it starts I would assume that I would need to replace the monovalve.

belt slipping????

if you go through a puddle and the belt gets water on it.... it will slip and disengage the compressor.. shut the car off and start it up...and the a/c comes back on...

wonder if it is doing that with slippage.....

That is true.....
 

I thought about that. But sometimes i don't have to drive through a puddle.. I could just be traveling on the interstate to work....

Low freon level is usually the issue, when you start the car low side is high enough to operate then pumps a while then high side is high but then low side is too low and clutch disengages to save compressor. R-12 can be found, find someone to top it off while runnang and make sure to fill it with clutch engaged and slowly work rpms up to 2k rpms so your system draws in enough freon.

Yea,

100F- I would at least check the freon to see if it's charged. Is your system still R12 or has it been converted?

Oh, yes there is a sensor on the compressor and if there is a speed difference between the engine and compressor- it cuts it out so you dont break the fan belt. Many times, it can be just an oily clutch which you can clean with break cleaner and spraying it down good. But fix the leak=(. If the clutch is worn too much, then you may have to re-shim it back to tolerance or by a new clutch assy.

Michael

Cool may be getting closer to the problem
 

The AC was converted back in 2005 to the R134 system...Would that be a problem?