98 C230 W202 A/C cycles and quits
 

My 98 C230 has been having A/C issues. Slowly it's gone from having great A/C to where it would only kick the compressor if I started the car with the AC on. Now it will come on, work for about 10 minutes then things get warm.

The compressor kicks in and out before it just stops.

I had a shop check it and they evacuated the system, did a pressure test and recharged and they said it has no leaks or level problems, they believe it's electrical.

I've tested the codes using the Climate Control Module and the following were the DTC codes that showed:

232 - Refrigerant Pressure Sensor
233 - Refrigerant Temperature Sensor
416 - Coolant Circulation Pump
417 - Left Duovalve (Water Valve)
419 - A/C Compressor Electromagnetic Clutch
451 - Diverter Flap
453 - Fresh/Recirculated Air Flap Long Stroke
454 - Fresh/Recirculated Air Flap Short Stroke

I reset all the codes and have run the test a number of times and I only ever get the 416 (Coolant Circulation Pump) code activating. While I may have a pump going out, I don't see that impacting my AC.

I've had the car for almost 2 years and the PO advised that they had just recently had the entire AC system replaced.

I figure I have a sensor that's gone or is going bad, but I'm not getting anything displaying to show that there is a problem.

Can anyone recommend some steps to help identify the problem child? Texas is about to get really warm, so I'd like to get this corrected as soon as possible. I bought this car because I didn't want to replace the AC system on the 300SD (I joke that I bought an AC system and it came wrapped in a Mercedes).

Any help or suggestions would be appreciated.

My car is much older (1990) but when my coolant recirculate pump froze up it took my climate control module with it. I wonder if it is causing some kind of protection mode? I unplugged mine. Austin is cold sometimes, but it blew plenty hot when stopped.

Other than that my a/c would cut out if the drive belt was slipping.

Did they do a pressure test while the AC was acting up? If high pressure is high and low pressure low, a likely cause would be a stuck expansion valve on the evaporator.

You could add an incadescent lamp across the clutch coil and see if:

Light is on but clutch is open = failing coil

Light is off but should be on = no signal to turn it on, look farther back. If the pressures look good, you could hot wire the clutch and see if it continues to cool. Also look at the condenser fans / engine fan, if they are weak you won't get much cooling at stationary idle.

Put a light across the heater valve, I think it needs power to close. I've added a ball valve to the heater hose opposite the stock valve to reduce thermosyphon when the engine is off.


For a hot climate, I'd unplug the pump. If it locks up it can hurt the HVAC control head. ( My 97 SL320 is unplugged and my 97 C280 is next )

I doubt the "entire AC system" was replaced. Doing so would include

Condenser
Condenser fans ( 2 )
Compressor
Hoses ( 5 )
Dryer
High pressure sensor
Liquid Freon temp sensor
Expansion valve
Evaporator
Evaporator temp sensor
HVAC control head
Outside temp sensor
Charge of freon
and a couple of other odd bits.

Hi All,

So I went out of town for work and when I came back I tried again. Cleared all the codes (only had the Coolant Circulation Pump on - History) and it's been working ever since.

Not sure what happened, but I'm cooling well now.

Weird....and why I hate AC issues.

Thanks for the responses, I'll keep them in mind for any future problems, but for now everything is working awesome.

Thanks,

Kevin