A/C compressor will not turn on

[fordguy87]

like the title says my A/C compressor clutch will not engage, we tested the connections under the hood with the A/C knob turned on and theres no current up there. We also did a direct wire off of the battery to the A/C compressor and it turned on so we know that the compressor is good. Is there any relays that could be bad somewhere? please help me out

 

[RUNINAGT]

Pressure switch ok??

 

[GearHd6]

Maybe your low on refrigerant? Jump the pressure switch plug on the accumulator/dryer with a paperclip and that should run the compressor.

 

[HISSIN50]

Agreed. If the LPS is ok, and you have adequate refrigerant in the system, check the WOT relay for vulcanized wiring.

Good luck.

 

[Daggar]

Agreed. If the LPS is ok, and you have adequate refrigerant in the system, check the WOT relay for vulcanized wiring.

Good luck.

Yup... once these little buggers get into your wiring, they can create all kinds of hate and discontent.

 

[bsedwebt70-5.0]

as was said earlier - I will bet you are low on freon - it has been this on EVERY 5.0 I have owned so far. I simply evacuate and retro-fit to 134 and charge it up myself.

 

[bubba-dough]

I would bet either low on refridgerant or its the pressure switch on the accumulator.

 

[fordguy87]

how do you know if the pressure switch on the accumulator is still good because i just filled the freon up after retrofitting to r134 and the gauge says its full.

 

[PuterAmI]

how do you know if the pressure switch on the accumulator is still good because i just filled the freon up after retrofitting to r134 and the gauge says its full.

With a proper set of gauges.

The low side should read ~90PSI at rest. When the system is turned on, you should see the low side fall to ~18-21PSI (R134A) before the switch turns the compressor off. The switch should energize the compressor when it rises back up to ~40PSI.

 

[rd]

If the refrigerant charge is too low, the low pressure switch will keep the compressor from engaging.

Most of the time, if you just add some refrigerant, it will put enough pressure on the system to turn the switch on, and then you can charge it.

 

[backfocus]

You can only truely tell your actual charge when the system is running. So if you are checking with your guage with the system not running, you really don't know what the real charge is.

Like they said jumper the LPS, if the system then runs, check the charge, check the vent temp, if all is well probably the LPS. If the system doesn't run jumpered, do as HISSIN says and check for vulcans!