No A/C in my 99

[silverado9984]

I have had the freon recharged and no a/c, I have had the compressor checked, the relay checked, sent the a/c control head in to be reconned and still no A/c. Does anyone have any ideas? Also, my mechanic can take his snapon computer and turn on the A/C and it blows cold air just fine.

[navysnipe]

It's probably your HP or LP switch. Try jumping out your LP switch with a paperclip and if it runs then it's probably that one. The LP switch is on the accumulator and the HP is really hard to get to on the compressor

Navysnipe

[silverado9984]

Before I sent the A/C control head in for recon, I jumped the low pressure switch and the relay and the compressor did not engage.

[75sierraclassic]

When you said you checked your compressor, did you check your coil that engages the clutch? I just found out mine is going out. I cut the plug at the compressor and spliced in two leads so i could monitor voltage at the coil. If it has voltage but is not turning on, your coil is probably bad.

[clinebarger]

Originally Posted by silverado9984

I have had the freon recharged and no a/c, I have had the compressor checked, the relay checked, sent the a/c control head in to be reconned and still no A/c. Does anyone have any ideas? Also, my mechanic can take his snapon computer and turn on the A/C and it blows cold air just fine.

Have your "mechanic" check for an A/C request on the Powertrain Control Module (PCM) data list (Yes or No).
If no A/C request, check for voltage at the high pressure cut-out switch or jumper the switch and recheck for A/C request. (The A/C request is ran through the high pressure switch on this model)



**A Snap-on scanner might not support this test**...I dont know what Snap-on Scanner or software version he's running. A Tech 2 will do this test.
Check the status of the A/C relay using the scan tool and reviewing Powertrain data. If the relay status is off...But the A/C request is yes...there is an input to the PCM inhibiting A/C operation.