1988 Air Conditioning Heat stuck on

[vigman]

Hi Guys.....

I share this tale of woah!
In my 88, after a long day at work I started the car & the heat jammed on FULL BLAST! Of course it was still 90+ outside.... I tried changing all the settings ( economy, defrost et al ) and all the doors opened & closed as designed. When I got home the A/C compressor was running, the low pressure lines were very cold ( sweating condensation ).. unlike me sweating normal sweat.

So I must have a door/flap problem or a control problem.

I read the shop manuals seeking the wisdom.. and I got some good ideas.

This is a " Auto " climate control ( C68 ).

There is a procedure to poke different buttons & have some remedial diagonistics.

On a Vert.. its HOLD Ext temp and tap AUTO.. this gives you a choice of options.. like error codes..

However everything ( as far as the brain..HA!) was concerned I was FINE!

So now the long take apart of the pass side dash ( 2+ hr ). I needed to see
what ( if anything ) the main temp door & control was doing ( or not ).
after taking out the top of the dash, bread box, lower carpet panel, ECM
and cursing the design team.

I can now ( ALMOST ) see the temp door motor & actuator looking from below.. I turn the ignition and rack through the temp settings 60-90 degrees... motor moves... ( this is good )
and back, again good. This motor controls ( internal to the A/C ductwork )
where the air comes from, either heater core or A/C condenser. I set the temp to 60. I restarted the car.... and another blast of hot air!~
:W:W:W:W:bash

I reached up to manualy feel if the linkage was moving.. and a tiny piece of white plastic fell to the floor.. the control arm was not attached to the control motor beacuse the .99 cent plastic/nylon clip went CRACK from age/heat. This " THING " makes the connection from the motor arm to the rod.

I moved the arm manualy and AHHHHHH COLD AIR..

So now I have to see where I can get a clip to make that work PROPERLY.hnoes any bets if GM still has it? ( I think not!)

Vig~

More to comead

 

[zrtwooo]

wow i feel your pain... i also have the 88 but the a/c wont auto climate control and a/c won't shut off unless i d/c the plug in the engine compartment... any learned wisdom would be a large help...i just took delivery on 8/17. and haven't really started the process of anything until i get some info on where best to start....
thx

 

[vigman]

88 A/C continued

The Local Chevy Dealer had NO IDEA what I was talking about and refered me to J&D corvette.... so off I went back to the garage.

The plan is:
the shaft has I believe threads for 10/24 ( well that nut fit's ok )

I cut a 1/2 bolt..about 1/2 of the shank, drilled a clearance for a 10/24.
tapped the bottom for a 8/32.. J&B welded a stud in the bottom.. found a bushing to make up the difference between the hole in the arm and the 8/32 screw, found some nylon washers so the new metal would pivot nicely as the arm went in and out. when I assemble I'll use 2 nuts on the air door shaft so I can adjust the open / close points.. then lock them down.. and all SHOULD BE WELL.. I'll wait till tonight to put the dash back together as it's another 98 degree day.. PLUS I have to P/U my kids Camaro from the local shop.

BAH

Vig~

Letting the J&B set up now

 

[vigman]

ZTR.. So what I'm understanding here is you have A/C ALL THE TIME.... reguardless of the temp control.. right?

Is it a manual ( Lever type ) or the C-68 digital? ( I believe you stated digital ).

A/C in AZ stuck on ... not such a bad thing LOL
So here's my questions.. Coupe or vert?

2nd question When you turn the car on.. do any of the lights flash on the climate control?

3rd.. When you change modes ( heat defrost etc ) do the position of the doors change?
In other words do you hear/ feel the air being re directed?

The C-4's use a combo of vacuume motors & electric motor to change things around.

if there is no vacuume getting to the controller ( under the dash ) on drivers side, on firewall over accellerator pedal ( If memory serves )... as you change modes... nuttin will happen.That Vacuume comes from under the dash.

Mine had a cracked line.. in the begining.

Vig~

 

[jmccloud]

Compressor always runs

This is like old home week. Several years ago Vigman really helped find why my compressor ran all the time. It was a shorted transister in the manual (C60) control head. That's correct - the manual control head is NOT a selector switch; it's a bank of diodes and transistor logic. The transistor that indicates A/C is desirable was shorted and always on.
So, zrtwooo, if you have a 'manual' A/C or an automatic, you may have a failed logic circuit in the control head. Hopefully yours will be as 'easy' to spot as mine was (after a lot of disassembly); the transistor looked like a peeled banana. $1 or so at Radio Shack and my compressor has since worked only when called upon.
Thanks again to Vigman for helping solve my first 'problem' with my 'new to me' happy sixtieth birthday '95 Corvette.
BTW, the clip that holds the temp control rod to the lever in the C60 control head is NOT as described in the Helms manual. I too have a creatively engineered fastener.

 

[vigman]

Cloud

Well I'm baccckkkkkkkkk

I'm starting to revive my babies.. did brakes on the 64.. only to find a pinhole in the radiator.. Grrrrrrrrrrr

I haven't put mine back together yet.. it was just to hot..

And had problems with the kids Camaro
AND
have to ADD my youngest son to my insurance policy
( which ment a 30 minute wrassle with my HP printer/fax machine)
Tomorrow AM is radiator day for 3 cars.

It just doesn't STOP!

Now I'm on hold with AAA for House insurance issues....:eyerole

 

[vigman]

Clips of death

and the mod

 

[vigman]

Whoops

Forgot how to download DUH~otfl

 

[zrtwooo]

thanks so much...

Vigman... it's a coupe
no lights flashing
no response in switching modes i.e. on off cooler hotter ect...
jmccloud: thanks you sound like you struggled with my same prob... it wont shut off even with the car off. it is onn ALL the time until i unplug the connection in the engine compartment...is there any other details that might help me find it more effectivly? by the way the auto climate controll doesn't work as well. most of the problems were told to me by my dad, the former owner...
thx
mike

 

[vigman]

Ok I'm confused

1st ) Does the display light up?
2nd ) Do you know how to retrieve the error codes from the Climate control?

Vig~

 

[badabing9]

i went through this 3 years ago and as for mine, the rod that goes into the clip at the actuator motor was somehow stripped out. gm no longer makes this clip so, i repaired mine. further research i found that advance auto parts sells the clip in a package of assorted clips that can be used to replace the discontinued one.

 

[zrtwooo]

Yes it does light up and i have no idea how to receive error codes from the a/c...;help

 

[vigman]

A/C error codes C68

Ignition on
press & HOLD rear defrost button ( Conv ext temp )
press & release blower fan UP ( Conv Auto fan )

this will give you a number preceded by a minus sign
eg -5

You are now in diag mode.

1 ) Program #
2 ) In car thermistor
3) Ambient correction
4) Blower number
5) Outside temp sensor
6) Feedback pot position
7)Calculated door position
8) System faults
9) Sw version #

Advance thru 1-9 by tapping the warmer button
Select the number you want to look at by hitting cooler.
( Go to 8 first )

Errors
00 = program number
01 = feedback pot open( on heater door servo )
02 = ambient sensor open
04 = ambient sensor shorted
08 = in car sensor open
16 = in car sensor shorted

Numbers other than this may show if there is more than one problem.


Start here....


Vig~

 

[zrtwooo]

holy cow!!!!

Thanks ****loads.
gonna go tyy it!!!!