Unplug the low pressure clutch cycling switch at the a/c accumulator and report back what happens with the fans.
Electric Cooling Fan Issue
- Thread starter tjd3004
- Start date
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Can you help me find this switch? I can hear my compressor turning on even when the heat is on so I'm hoping this will fix my problem!
At the a/c accumulator. That is at the firewall at the passenger side of engine compartment. It is an aluminum cylinder that attaches at a feed tube thru the firewall and hose ran to it. Should be a switch threaded at the top side of it with a plug in. Unplug that. The reason the compressor cycles is that the defroster is on instead of just heat.
Also your compressor will cycle when you have the recirculate button on... Figured that one out too.
But you wouldn't have the recirc button on unless the a/c is on, right? Unless he doesn't shut it off during fall and winter? Just asking because am unsure.
Hmm Yea, try that switch and report back.
Then like scoobyxj said, I would lean toward this coolant temp sensor. Not the sender for the dash but the sensor that feeds info to the computer.
---------- Post added at 08:32 AM ---------- Previous post was at 08:27 AM ----------
AC Deco part #2134333
The computer appears to be commanding this. 2 reasons come to mind, one its getting a false reading due to an air pocket in the cylinder head (very common for read temp to spike on a gauge while actual temp is low due to a false pocket of steam) or 2 a false high reading due to a faulty sending unit. First one is free to try and second will cost $15 or so. Reservoir and radiator being full doesn't mean there isn't air trapped in the engine.
---------- Post added at 05:12 PM ---------- Previous post was at 05:09 PM ----------
Also, I'd have to confirm at my laptop but I think high fans will be commanded with an excess of AC pressure. So whatever sensor reads AC pressure could very well be faulty throwing a false high. Need a scanner to verify this. There are only a couple of reasons why this is happening....not hard to diagnose and not just throw parts at the truck.
---------- Post added at 05:12 PM ---------- Previous post was at 05:09 PM ----------
Also, I'd have to confirm at my laptop but I think high fans will be commanded with an excess of AC pressure. So whatever sensor reads AC pressure could very well be faulty throwing a false high. Need a scanner to verify this. There are only a couple of reasons why this is happening....not hard to diagnose and not just throw parts at the truck.
