06 AC Info needed...

Well tickle a pickle, I bet your thinking OH BOY ANOTHER AC THREAD! Well, sorry bro my searching skills have failed.... I'm trying to trouble shoot my AC issue while out of work (thanks covid-19) and I'm needing some info I cant seem to find...

Symptoms: AC worked perfect one night, next day hot as balls! Never attempted to work since. This was over a year ago, never messed with it due to cold weather. Anyway, AC light is solid/NOT blinking. I cant see, hear, feel etc the compressor clutch engage or anything.... hooked a cheap gauge to the low PSI port and it showed 40 at idle with the AC controls set to full tilt, yeah i know they are not very accurate but still.. Just for curiosity sake pressed valve with a screw driver and shes not empty.

TL;DR: Ac out, no blinking light, cheapo china gauge shows 40

How do i go about manually engaging the clutch? I've seen it mentioned but cant exactly find a diagram to find which wires to jump? What would you check next? I believe 40 is correct for low side pressure.

 

You should be able to tell if the compressor is on by looking at it. With the engine running, turn AC off and look at the front of the pulley, it shouldn’t be spinning. Then turn Ac on, it should click on and start spinning.

If it does click on, feel the ac hoses to see if they are getting hot/cold. Skinny hoses should be hot, fatter hoses should be cold.

If they are all regular temp (not hot or cold) either the compressor is not on or it is not functioning properly.

If the low side hoses are cold, it means the compressor is functioning and you likely have a blend door or actuator issue.

Hope this helps.

 

Yeah the first thing i did was have my wife turn on and off the ac switch while I watched the compressor. Its not activating for sure. thats why i was trying to find which wires to jump to force it to engage. Im trying to trouble shoot the issue and replace parts before having the system e-vac and refilled. I'm a mechanic by trade (heavy equipment field mechanic) but I usually dont mess with AC systems. The 10a fuse in the box under the hood is good, I replaced it anyway. Correct me if im wrong, but if the MG CLT relay was bad wouldnt I have the flashing ac light?

 

I'm not sure about the flashing light due to a bad relay, most of my AC repair experience is on GM vehicles and they don't have that feature. The easiest way to test the clutch coil would be to ohm it out first, if it's open or shorted, there's your problem. Otherwise you can apply 12V to it to see if it engages. It should be relatively easy to see the wires coming out of the back of the clutch coil, follow them to the nearest connector and test accordingly. Just be careful if the coil is shorted and you apply voltage you could burn the wiring, so I'd recommend a quick resistance test first.

 

Another thought I'm having here is that if your pressure gauge is reading 40 on the low side with the compressor ON, that seems like a reasonable number depending on ambient temperature. But if the compressor is NOT coming on like you said, 40 seems too low. IDK what the outside temp is when your taking this reading but I'd like to see closer to 70-80 psi with the compressor off. When it kicks on, low side should drop to the 30-40 range with high side close to 200.
Edit: I'd check for leaks anyway, a common leak location I've seen on our trucks is at the plastic clamps on the hoses near the firewall going to the evaporator.

 

Jumper your A/C clutch relay contacts pin 3-5 and see if the compressor kicks on. Before you do that, have a pal press the A/C button with the engine running and see if you can feel the relay click. Remove the relay and energize the coil, check contact resistance. But if you see the compressor engaging when you press the button then you can eliminate that. If your clutch is not not engaging, it could be the pressure cutout keeping it off, after you check the relay, jumper the pressure switch contacts on the passenger side and try to start it (very briefly) and see if the compressor engages.

 

6 Gear,

Sorry to bother you but I am having a very similar issue. Same symptoms as OP, however I have not checked my pressure, and I have replaced the relay because I did not feel it click. Would you recommend jumping the relay? I cannot find my multimeter anywhere though... So take a wire and put between 3 and 5, correct?

 

Yeah. 3 and 5.

 

sorry I didn't see this until now, yes jumper a wire between 3 and 5 terminal and it should pick up the compressor. Have a buddy watch from underneath, or set up a camera, the clutch hub only moves a small amount when the clutch is energized.