A/C not working. Clutch is not engaging

[Modoyadney]

Hi,

After fixing the problem with my rear O2 sensors, I wanted to bring the A/C back to live, especially now in the summer...

The old compressor was stuck, so I installed a new compressor, new A/C lines, new condenser and a new drier last weekend.
I filled it up today, but when pressing the A/C button the clutch won't engage. I've already checked the fuse and relay.

When using a jump wire at the fuse box, where the relay goes, the clutch engages.

Has anyone an idea where to start looking here?

 

[Modoyadney]

The truck is a 99 Suburban, forgot to mention that.

I tried to follow the wiring from the HVAC control module on.
But the A/C High Pressure Switch is nowhere to be found on my system. The manual states it's supposed to be on the backside of the compressor.
My new replacement compressor nor the original one have this switch.





I've alraedy tried to disconnect and put a jumper on the cycling switch on the accumulator as well, but this also didn't make the clutch engage.

 

[east302]

Did it come with the snap ring and plug? That comes out and the switch goes there.



The harness splits into four at the EGR valve. The wiring across the compressor goes to that switch, the other three to the coolant temp sensor, the EGR and to the compressor clutch.

 

[Modoyadney]

Hi,

Thanks for your help. I managed to find the problem.
It seems like one of the previous owners has messed with the system.
Thats probably why the sensor was missing on the old compressor as well. I found the cable and connector tucked between the valve cover and intake.

Right now I used a jumper to make the system run.
I might order a new switch. Can it be installed with the system charged and compressor installed in the vehicle?

 

[east302]

It doesn’t have a schrader valve like the one on the accumulator (it’s held in by that snap ring) so I’d think that you would lose refrigerant.

 

[OR VietVet]

Yes, you lose all the refrigerant. Evacuate the system and hold the refrigerant. swap in the switch and make sure the o-ring is good. Hard to see in there so may be best to unbolt and tilt so can see and work better and that will also allow for no oil spillage. Reinstall, evacuate and keep on vacuum for 30 minutes since the accumulator is fresh, IMO put a new low pressure/cycling switch on too and you did not say you installed a new orifice. If you did not, do so now before pulling the vacuum. Make sure the system holds vacuum for 10 minutes. Then charge the system and put on a heavier coat. One thing I would have done is flush out evaporator, did you. Shame if you did not.

 

[Eman85]

Every time I replace a compressor I use a new high pressure cutout switch, usually the old one is hard to get out and not worth the aggravation especially if it fails. As stated you have to discharge the system to install/replace the high pressure switch. Also as stated the orifice tube and condenser & evaporator flush is required for the life of the compressor.

 

[Modoyadney]

I guess I'll have to add this to my to-do list, since I don't have the equipment to evacuate the refrigerant without loosing it.
But I forgot to mention that I replaced the orifice tube as well, since it was included within the new A/C line.

I didn't flush the evaporator, because I thought if there were any residues from the broken compressor, it should be stuck in the old lines and especially the old orifice tube.

 

[OR VietVet]

I guess I'll have to add this to my to-do list, since I don't have the equipment to evacuate the refrigerant without loosing it.
But I forgot to mention that I replaced the orifice tube as well, since it was included within the new A/C line.

I didn't flush the evaporator, because I thought if there were any residues from the broken compressor, it should be stuck in the old lines and especially the old orifice tube.

Go to a shop that you trust. Work out a deal for them to recover the refrigerant and that machine can measure what amount is removed. Do the switch replacement and the flush. bring back to them for the vacuum and the recharge. Work out an agreed upon price to do that. In KC, Mo. I did that at my shops.

 

[j91z28d1]

if you follow the high pressure hose from compressor to the condensor, some have a high pressure port with a Schrader valve in it on the inlet side, so you can just screw it on. you'd have to run longer wires, and a different style sensor.. but can be done. mine had it over there. running it without a high pressure cut off is kinda scary. if something happens 400 psi bursting a hose isn't great.