one of the issues i have with my new 928 is the climate control.
when i was talking with matt about the car, I was told everything was working, climate control, seats, etc...

well i get there and there are a few.. oh yea, i forgot that ____ does not work..

I do not think Matt intentionally misrepresented the car at all. I know that owners often forget about the nonfunctional stuff...

The climate control was one of the issues. EVERY climate control had problems on every other 928 i looked at, so i figure i am not out any more than i would have been with any other car... ALso Matt offered to split the cost of the unit if it needed replacing.

Here is the issue with the unit...

the lights on the unit are non functional.
moving the floor, bidirect, defrost lever does not appear to change where the air comes from. The defrost position all the way over does work however.. it turns the fan on wide open and kicks on the AC. The ac switch works and the fan speed **** works...

also the air temperature does not change when moving the temperature slider.. it blows barely warm...


What can i do to check things out before just ordering a new climate control unit, or sending this one off for a rehab? Any fuses, relays, etc that would cause these issues?

other issue is the drivers side back seat switch face had broken off... so if anyone has a spare laying around i would love to buy a used one.

 

It's much more likely that you have problems in one or more of the vacuum actuators (or perhaps the solenoid switches) selected by the control unit, rather than a problem with the unit itself (the non-functional lights are likely just a blown bulb - there's one bulb that illumintaes things via fibre-optics).

The good news is that removing the control unit, opening it and changing the bulb is pretty easy!

The bad news is that you need to do a methodical check of the whole HVAC system (most useful tool here is Mity-Vac for applying an d checking hold of vacuum) to see root of problems. This will entail removal of console sides for checking vacuum lines, and then possibly removal of centre console and/or other dash parts to replace any leaking actuators.

There are great write-ups by Dwayne (google Dwayne's Garage or check the tech tips area of Rennlist as it may be posted there or just search this forum) and on John Pirtle's site for testing and troubleshooting hvac system. Try to get Wally Plumley's paper too on how the whole shooting match operates.

You need to go through things logically starting with order in which you check the vacuum system itself, and then individual vacuum lines. Once all well with actuators/solenoids you may have to dive into testing the internal and external (common failure point) sensors.

I've seen scores of posts about leaking vacuum actuators/solenoids, for every one describing problem with control head itself. In fact I can hardly remember seeing anyone reporting problem with control head aside from the well-known aircon relay failure in that unit.

Good luck and keep asking questions as you get into the system!

 

Impossible to give much help without knowing the model year...

 

it's an 87...

i just found several write ups on this topic.. originally i searched for "climate control problems" and came up with very little.... found a ton of stuff under hvac..

i have a vac pump and will get to work........

 

If non of the vacuum opperation is working the first place I'd check is the vac supply line where it attaches near the brake booster. No disassembly required, just a flashlight.

 

It seems to be a common issue with the S4 in particular, my 1988 HVAC system is still a little weird even though the PO had it completely taken apart and repaired.

 

There are four vacuum actuators for the flaps, which all contain relatively thin diaphragms. Those tend to dry out and crack or tear with age. Similarly, the heater valve (under the air filter) often does not work properly.

None of them will work, if there isn't enough vacuum because of leaks earlier in the system.

Based on what I've learned, a good place to start are the many rubber connectors in the vacuum system - if those have hardened, they won't seal properly. If they are hard and old, it might be a good idea to replace them all preventively.

Look for the 4-way vacuum connector near the brake booster, and the check valve. Look for the rubber elbow and the rubber manifold at the solenoids in the console (you have to remove the drivers side console panel to access them - I had leaks there). Don't forget the rubber seal at the vacuum canister under the left front fender - mine leaked badly.

Hope this helps!

 

go to user CP at the top of the page click on it then look for edit signature Please add you year and model and trans type and any other info.
Then go to 928gt.com on page 2 click on tips and links look for Wallys HVAC system repair tips

 

k.
got the signature fixed... sorry bout that..

i was only able to check the black vac line from the four way to the climate unit...
all good there. i also checked all the other hoses while i was at it... all good

tomorrow i will start checking individual lines inside.

 

When you say all good did you:

- pump vacuum on that line and confirm it holds (ignition off)
- with vacuum on that line turn ignition on
- vac still ok?
- what happens when you move hvac selector lever to different positions?

 

well i found ONE of the issues just now... the heater valve is backwards....LOL...
MATT...you goofball....LOL..
according to the post
http://members.rennlist.com/pirtle/svc_act.html
the actuator arm should be on the engine side of the valve, the pic in that thread also shows the arm above the valve... on my car the actuator arm faces the firewall and is under the valve... I am waiting for the car to cool down before i switch it... kinda hot back there..

 

well... guess mat isn't a goober after all...
according to the post sited above the valve is unidirectional.. not true..
mine is a straight through valve, does not matter which way it goes in...
is is TIGHT getting back there... but at least i tested it when it came off and it functions great with the mighty vac... no issues there..
BUT i found some leaks.

when i tested the black supply line feeding the hvac at the brake booster it held vac. I turned on the key and vac dissapeared.. no matter what position the temp slider was in.. leaking vac..

looks like i am tearing into the center console side panel....

 

How do I get the air conditioner control unit out of the consul? I cannot get the plastic ***** off the control sliders? I tried pulling them by hand, plier, no luck. What am I doing wrong? Any ideas?
I'm having trouble with my Air, mechanic says its the relay on the control panel. He prefers not to do it so I will. Found the info on using the Radio Shack Relay but can't get access.

 

I think there is a write up which is very detailed by Dwayne.
You need to pull the center vent
You need to gently remove the plastic H
Remove screws and remove the controller.

 

I'll try that, the H sits behind the consul upholstery, do I just pry it out?