jpuzas

Car: 87 S4
Problem Statement: HVAC intermittently works. Sometimes everything works fine and sometimes it is completely dead

Details: When it is not working nothing works. Blower does not blow. Blower does not blow on Defrost. A/C button does not light. No air is moving. When it works everything works. Blower blows on all positions. Temperature control works blows hot when slider on hot cold when on cold. A/C works fans come on. I can hear the flaps moving and all flap positions work. I haven't been able to identify a pattern of when it works and when it does not. Seems to be random.

Question. I have read Wally's paper on operation and searched the forum for similar problems and could not find one that had a solution. Does anyone have any ideas on where to look?

Thanks in advance,
Jeff.

thundershark

[QUOTE=jpuzas;8981416]Car: 87 S4
Problem Statement: HVAC intermittently works. Sometimes everything works fine and sometimes it is completely dead

Details: When it is not working nothing works. Blower does not blow. Blower does not blow on Defrost. A/C button does not light. No air is moving. When it works everything works. Blower blows on all positions. Temperature control works blows hot when slider on hot cold when on cold. A/C works fans come on. I can hear the flaps moving and all flap positions work. I haven't been able to identify a pattern of when it works and when it does not. Seems to be random.

Question. I have read Wally's paper on operation and searched the forum for similar problems and could not find one that had a solution. Does anyone have any ideas on where to look? My 82 had a similar problem.

I found the blower fan connection near the passengers side wiper area had a bad connection at the terminal, just wiggled it around some and everything began to work. Marty

StratfordShark

Possibly one of two edge connectors loose at side of controller? Remove the H trim around heater controls, take out 6 screws holding in ac switch console and hvac controller, pull out a few inches and check the connectors firmly home.

Alternatively remove one carpeted side panel and push connectors from the side. My car is RHD and the edge connectors are on the passenger side. Presumably you need to remove driver side of centre console?

Alan

When it doesn't work - do the fog light work?

Alan

jpuzas

Pretty sure your busting chops But I will give it a go. I have not tried that one. Will do today and will report back. The connector suggestions sound more likely to bear fruit but sometimes things are interrelated in wierd ways such as the brake light bulb affecting cruise control so I will try anything. My guess is the connector onto the controller coming loose.

rbrtmchl

jpuzas,

Alan is not busting your chops. If your Ignition-X relay (position IV) is not working properly, this can cause your HVAC and your fog lights to not work properly. See this recent thread:

https://rennlist.com/forums/928-foru...ans-fixed.html

jpuzas

So..... Drum roll please.... I was the IV position on the ignition switch. Got in this morning and tried the HVAC and it was dead. Turned on the headlights and what.... no foglights! Go back in the car and jiggle the key in the ignition and the HVAC fires up! Worked the whole drive to work today. Thanks a bunch guys! This list is amazing! So I guess the fix is a new ignition switch? I have read posts in the past where one can get one that will work with the same key. Any guidance on how to keep the same key? I had a new one made about 50,000miles ago and I use it.

Thanks,
Jeff.

Mrmerlin

you dont need a new key.
just the electrical part of the ignition switch,
its a 2 part piece,
the switch plugs into the back of the key cylinder and its held on with 2 screws.
Buy a switch from a known vendor as they was a batch of them that were bad from the MFG source most have been taken out of the supply chain.
Disconnect the battery before removing the pod bolts