diehlryan

So I've reported a cooling issue the last few days which I am slowly getting narrowed down.

I'm fixing the fan module, thermo switch, most likely fan, and I also think I'm having WP and Thermostat issues. I'm 10k away from needing a 2nd timing belt change so I'll do that early.


On to the most recent issue with A/C. When idiling I can hear the compressor cycling on and off every few mins. This is also noted in cool air, warm air, cool air, warm air. When cruising down the road the A/C is fine and blows cool/cold air.

Help!

InTTruder

Check the compressor charge Ryan?

diehlryan

The A/C isn't as cold as I would like and had thought about it needing a recharge.

InTTruder

Unless you have tools, or a friend with them, take it to a shop (Indie).

DasTT

Are the fans working yet? If not, then you answered your own question.

You could be low on charge, but get radiator fans working first.

diehlryan

2nd.. Its the compressor kicking on and off.

diehlryan

Thanks for the input. Obviously this means I'm out for QDM.

DasTT

The outside temp and humidity will have a lot to do with how the A/C performs. Checking A/C performance is done this way:

Fully warmed up engine
A/C on Auto, recirculate
Temp set to "lo"
Doors/windows closed
All vents open
Hood closed
Both coolant fans running at speed 1 or better.
BTW, your coolant fans are wired in parallel, so if one is not running and the other is, you have a bad fan.


Measure outside temp
Put your temp probe into one of the center vents
Start engine, start a clock and set engine to 2000RPM

After 5 minutes, measure center vent temperature

Your A/C is fine if your center vent temp is between 37 and 43 degrees if the outside temp is 90 or below.

Above 90 outside temp, you can degrade the center vent temp about 20% of the outside temp above 90.

The system on the TT is designed to cycle the compressor based on the evaporator temperature or the high side pressure. You'll get cycling based on high side pressure being too high if you don't move air over the condenser. You'll get cycling at the evaporator temperature of 34 degrees.

Oh and yes, I am an A/C technician.

mobsTTa

My exact symptoms: Fine one day, then no cold air. All of a sudden, dash flashes temp gauge almost pinned, beeps, pull off highway. Vent the overflow, blows off about a pint. Diagnosed as Fan Control Module. Check yours.

diehlryan

replaced already. no dice.