No ac..some ac..nothing.....

98 Jimmy 4.3

Yesterday after 30 mins of running up the highway, my AC stopped blowing cold. I let it sit thinking I needed freon. Today I started it and all was well. 30 mins later off agian. Starting working itermently.

Max AC- Blower High (all speeds worked)

Max ac, no blower(all speeds)

norm ac- blower (all speeds Worked)

Ac worked -no blower

Nothing now. Will try later.

I really dont know where to start looking with it all acting up at once.

Thanks for any help.
Andy

Ok, i tried again about 4 hours later. NOTHING is working now. Fuses seem to fine.

Auto matic or manual controls?
Does the AC compressor quit at the same time blower quits?
Does blower lose all speeds at one time?

Does AC get cold when it does work?
Any check engine or flashing ac lights?

Auto matic or manual controls?
Does the AC compressor quit at the same time blower quits?
Does blower lose all speeds at one time?

Does AC get cold when it does work?
Any check engine or flashing ac lights?


Manual controls
Not everytime
Yes all at once

Yes very cold
No no lights at all.

Check for good 12 volts both sides on hvac fuse 9 in ip fuse box.
Make sure it does not lose voltage when compressor or fan quits.
You could have a lose/bad fuse or power to fuse.
If that is good

Then pull HVAC ac controls.
Check for plugged in good or lose connection on back of mode switch.
The hvac fuse feeds 12 volts one on of the brown wires to mode switch.
Mode switch turns on ac compressor and fan circuit.
The other brown wire on mode switch feeds fan switch.

On AC or defrost the light blue wire from mode switch should be hot for compressor.
On any position but off the brown wire from hvac mode switch feeds the blower switch circuit.

Find out if you are losing 12 volts into the switch or out of it on light blue or brown wire to fan switch.

If good voltage into the mode switch and no voltage out
It is a bad switch /HVAC control.

Post back what you find.

One thing I forgot to mention was the relay under the hood. I changed it with the one for the horn, they were the same kind. It worked for a lil bit then shut off again. I put the realay back in the horn side and it worked, both relays worked.

not sure if that helps but i thought it was worth mentioning.

THANKS FOR THE HELP!!!

I had a few minutes so I pulled the fuses again and tap on the relays. Both were working fine after that. I havent investigated further yet, but i will keep you updated.

The part that is giving you problems is not relayed.

You are losing power to the switch or the switch is not switching right.
Get out the old test light or volt meter and fin out where.
Good Luck
MT

I have been having the same problem. There are 3 relays on the firewall close to the blower. 1 wire was hanging out of my plug and it would wiggle and touch and the ac would work, then next thing you know NO AC because it had wiggled and came lose. I found this problem today and it fixed all my problems. Worth a shot man.

Good Luck

Check for good 12 volts both sides on hvac fuse 9 in ip fuse box.
Make sure it does not lose voltage when compressor or fan quits.
You could have a lose/bad fuse or power to fuse.
If that is good

Then pull HVAC ac controls.
Check for plugged in good or lose connection on back of mode switch.
The hvac fuse feeds 12 volts one on of the brown wires to mode switch.
Mode switch turns on ac compressor and fan circuit.
The other brown wire on mode switch feeds fan switch.

On AC or defrost the light blue wire from mode switch should be hot for compressor.
On any position but off the brown wire from hvac mode switch feeds the blower switch circuit.

Find out if you are losing 12 volts into the switch or out of it on light blue or brown wire to fan switch.

If good voltage into the mode switch and no voltage out
It is a bad switch /HVAC control.

Post back what you find.

Well I did do all this and everything checked out ok. 12 volts to all. The a/c and blower have not stopped working again yet so I might need to check after it stops. Anything else? Thanks!!

You need to check it when it quits.
Good Luck
MT