2003 Tahoe LT - AC frustrating
Let me start by saying I'm no mechanic, not even close so ve gental on me....
so AC is touching hot air ... I have replaced everything I can think of
accumulator
compressor
air lines lines
Belts
bottles and bottles of 134a
go to all the pretty gauges
blows hot still and overheats at idle.... never get cold all gauges read as (youtude tells me these should be)
so AC is touching hot air ... I have replaced everything I can think of
accumulator
compressor
air lines lines
Belts
bottles and bottles of 134a
go to all the pretty gauges
blows hot still and overheats at idle.... never get cold all gauges read as (youtude tells me these should be)
-put the gauges note the static pressure (pressure with the system off for 10minutes) and ambient temperature. post results.
-start the engine and run the a/c system; does the compressor run, does the compressor short cycle? turn on for 5-10seconds and then shut off.
-does the high side pressure go over 250 psi pretty fast
-are the cooling fans turning on?
-start the engine and run the a/c system; does the compressor run, does the compressor short cycle? turn on for 5-10seconds and then shut off.
-does the high side pressure go over 250 psi pretty fast
-are the cooling fans turning on?
System off blue Line reads 51 red is at 50
The compressor does not run when the air conditioner is on it will turn on the second I turn the air conditioner off
When I turn the AC off the red line goes up to about 125 and blue side drops to 20 and then goes back and sits around 58
Radiator fan is not on and it's the compressor Cycles about every 5 to 10 seconds like you said
Last edited by Joe Knudsen; Jun 6, 2018 at 3:26 PM.
Thanks for any and all assistance
the first thing to address is why the ac is coming on when switched off and why it off when switched on.
how I think it should work is the a/c "on" switch grounds a signal from the pcm. the pcm provides power on the wire to the ON switch...the wire then goes to the pressure switch then to chassis grd...so if you check the wiring at the hvac module c1 connector... pin b11 white wire should have power from the pcm and the a12 dark blue wire should have grd if the pressure switch is closed(its closed with the system charged with refrigerant)
do you have automatic or manual system?
how I think it should work is the a/c "on" switch grounds a signal from the pcm. the pcm provides power on the wire to the ON switch...the wire then goes to the pressure switch then to chassis grd...so if you check the wiring at the hvac module c1 connector... pin b11 white wire should have power from the pcm and the a12 dark blue wire should have grd if the pressure switch is closed(its closed with the system charged with refrigerant)
do you have automatic or manual system?
Last edited by tech2; Jun 6, 2018 at 8:24 PM.
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Isn't the clutch just a solenoid that pulls in? I wouldn't think it would be more complex than a power and ground engaging it, and even if it was plugged it backwards, I don't see how it could ever engage?
I wonder if there is a wrong relay in the fuse box or something? Something that is normally closed when it should be normally open? That would explain reverse operation of the switch. As for the fans not coming on...somewhat of a mystery there.
I wonder if there is a wrong relay in the fuse box or something? Something that is normally closed when it should be normally open? That would explain reverse operation of the switch. As for the fans not coming on...somewhat of a mystery there.


