AC troubleshooting tips

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AC troubleshooting tips

Postby smfsfearmii » 24 Mar 2015, 14:00

So I know it's not the "correct way" to conduct a recharge of the ac system but I do a few things before I try and bust out the complicated time consuming equipment and I can usually get an ac system up within 20 min.
•test to see if compressor is engaging. Turn blower and ac switch on and temp control to cold. compressor should engage.
•if not have a 4 inch jumper wire. Unplug the low pressure cutoff switch. Jump the wiring harness connector with the previous step done.
Compressor should engage. If so, add refrigerant. If not proceed to next step.
•test power to the compressor when the the ac and blower is on. Should read battery voltage. If not trace the problem for that. Switch, relay, wire, etc. if that was the problem repeat previous steps.
•if you have battery voltage, and compressor is not engaging, with the jumper wire, try charging with the jumper wire in place. If it does not engage replace compressor.

****you cannot manually test pressure without the compressor engaging.****
****never purge refeidgerant into the atmosphere****
The reasoning behind the jumper wire is if it has too low of pressure it will not close the circuit to allow compressor to run. Jumping this forces the compressor to run if it has low pressure and you can test the pressure of the high (red) and low (blue). If it's lower than 35psi with compressor running charge the low side and it should even out the high side to correct pressure. If you test the psi with compressor off the low side will say 90 psi or something crazy like that. Please feel free to chime in if I have displayed any incorrect information.
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Re: AC troubleshooting tips

Postby SUPERMOD » 25 Mar 2015, 07:11

Great to know. thank you!
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Re: AC troubleshooting tips

Postby Grandpa3523 » 07 Apr 2015, 07:47

ON HMMWV's CHECK THE THERMO SWITCH, IT'S LOCATED ON THE SIDE OF THE FRONT EVAP BOX, (SMALL BLACK BOX WITH 3 BLACK WIRES AND 2 SMALL WHITE WIRES) UNHOOK THE TWO BLACK WIRES ONE MALE ONE FEMALE, CONECT THE HARNESS SIDE WIRES TOGETHER. IF COMPRESSOR COMES ON REPLC THERMO SWITCH, ITEM 4 FIG 287A 01-539-7057. ****IMPORTANT*** WHEN IN DUBT OF R134A CHARGE RECOVER AND RECHARGE WITH PROPER AMOUNT, IT ONLY TAKES ABOUT 45 MINUTES AND CAN HELP WITH MULTIPLE AC ISSUES.
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