1994 E320 Wagon
223,000 miles
new evap and expansion valve 3 years ago
blower motor good, possible fault with vac pods on fresh/recirc flap

Symptoms:

AC cools very well when car first started. Sometimes, AC will slowly loose cooling efficiency after 20 to 30 minutes. Under hood inspection sometimes reveals white frost/ice on low side plumbing between expansion valve and fuel cooler. Also, when switching to EC mode, some cooling can still be felt for up to 10-15 minutes after switch to EC. Climate control module gives 1 blink when checked for codes. (however, home brew code reader led stays on dim after giving one bright flash.......not sure what that means)

I suspect evap freezing caused by a faulty evap temp sensor.

Question for the experts: Is it possible that a faulty expansion valve could cause this problem, or is it more likely that the evap temp sensor is bad?

My plan is to check (with Ohmmeter) the temp sensor and compare to spec values from the service CD.

Any other suggestions or comments?


Thanks,

J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles