A/C Woes

[bmcgc]

The AC in my wifes 99 quit working. She says the blower still worked. The airbag light occasionally started coming on for a couple days, then it would go out. IDK if that is related, but it started around the same time as the AC quit blowing cold.

I went out this morning to troubleshoot.

The compressor clutch is not engaging. The blower motor is now not working.

I swapped the relays under the hood between the horn and AC, the horn worked with either relay.

IDK which fuse under the hood is for the AC, so I put a test light on all of them and they all work.

The fuse box behind the glove box has no power to #7 or #8. They did have power when I installed the radio because I checked them all.

Why would the blower fuse not be getting power?

Any suggestions on my next move?

 

[Chris]

The AC in my wifes 99 quit working. She says the blower still worked. The airbag light occasionally started coming on for a couple days, then it would go out. IDK if that is related, but it started around the same time as the AC quit blowing cold.

I went out this morning to troubleshoot.

The compressor clutch is not engaging. The blower motor is now not working.

I swapped the relays under the hood between the horn and AC, the horn worked with either relay.

IDK which fuse under the hood is for the AC, so I put a test light on all of them and they all work.

The fuse box behind the glove box has no power to #7 or #8. They did have power when I installed the radio because I checked them all.

Why would the blower fuse not be getting power?

Any suggestions on my next move?

The fact that the blower motor isn't working and that the compressor clutch isn't engaging could indicate a few different problems.

Here are a few suggestions you can try:

Check the Ground Connections: Ensure that all ground connections related to the HVAC system are secure and free of corrosion. A bad ground can cause multiple electrical components to behave erratically.

Inspect the Blower Motor Resistor: If the blower motor won't turn on at all, the blower motor resistor could be faulty. Sometimes they can cause the blower to only work on certain speeds or not at all.

Wiring Issues: Given the intermittent nature of your airbag light and blower motor, inspect the wiring harness for any signs of wear, fraying, or corrosion. A short or poor connection in the electrical system could be causing these issues.

Test the AC Switch and Climate Control Panel: It's possible that the switch or climate control panel is malfunctioning. If you have access to a multimeter, test that the switch is sending power to the blower motor.

AC Relay: Even though you've swapped relays and checked the fuses, the AC relay could still be faulty or there could be another relay in the circuit that is failing. Check any related relays that might affect the blower motor.

Check for Codes: Since the airbag light is coming on intermittently, it might be worth checking for any diagnostic trouble codes (DTCs) that could point to the problem. Sometimes, issues in one system can affect another.

Fuses and Power Distribution: You mentioned you're not getting power to fuses #7 and #8 behind the glove box. You might want to trace back from those fuses to see if there's a specific connector or junction block that’s not getting power.

 

[DuckNut]

If your system is low on freon, the compressor will not engage. Focus on the fan and then move to the ac.

 

[txbemis69]

you can unplug the low pressure switch and jump the plug with a paper clip to see if your compressor kicks on. my a/c went out last summer and it turned out to be a faulty low pressure switch. i’d recommend this after sorting out your blower motor issue first.

 

[bmcgc]

Now that I think about it. When I installed the HU, the 3-prong HVAC plug had melted and a PO did a hack job repairing it. I'm betting that is where my problem is. I will pop the bezel off tomorrow and see if the plug has disconnected itself. I may have to figure out a better solution than what is currently there.

 

[Cooper Smith]

Now that I think about it. When I installed the HU, the 3-prong HVAC plug had melted and a PO did a hack job repairing it. I'm betting that is where my problem is. I will pop the bezel off tomorrow and see if the plug has disconnected itself. I may have to figure out a better solution than what is currently there.

Yep, get a pigtail. I prefer soldering and heat shrink as an electronics tech, but most people don't like and it's hard to do a good job in cramped areas. I like the heat-shrinkable butt connectors. Those are essentially a lifetime crimp, not a "it'll work till the wire corrodes" kinda ordeal.

 

[bmcgc]

Update:

I had to put this on the back burner for a few days. The HVAC controls work as they should. All fuses and relays seem to be good. The high and low pressure switches have continuity.

My SIL has a set of gauges and I will check the coolant charge this weekend.

Meanwhile, I put my hand on the AC clutch and it slightly rocks back and forth. That doesn't deem normal, Shouldn't the clutch be rock solid with no play?. Could I have a bad clutch?

 

[bmcgc]

 

[JKP]

The clutch is disengaged.

When AC is selected, the electromagnet pulls the clutch together.