Auto heat troubleshooting

Wil Ferch · 09-15-2002, 11:55 AM

Guys:
I don't have heat in my 85 Carrera with auto temp control.
Thr engine mounted blower works, the footwell blowers work...
When I dial up 6-7-8-9 ..especially at 9 I get max flow from all blowers..but no heat.
I'm constantly under the car and heater cables ( and movement) on the flapper valves were ( still are?) OK.

I'm suspecting the road actuation of the servo motor in the console between the seats...maybe the temp sensor at the flapper valve or in the cabin.

What's the proper sequence to diagnose this ??

Wil Ferch

Paco Anton · Paco Anton's Garage

Anybody?

I have exactly the same problem and winter is approaching!!!!

LeeH · 09-25-2002, 07:02 AM

I had the same problem and it turned out that the rod connecting the servo to the cable came off. If you remove the rubber around the e-brake you should be able to shine a light in there and see if it's connected. The reason mine came off is that the flappers were sticky. A little WD 40 on the flappers and in the cables solved that problem.

Sean Hamilton · Sean Hamilton's Garage

Yup, ditto Lee.

Quote:

Originally posted by Wil Ferch
........What's the proper sequence to diagnose this ??

You'll here the servo motor whirring away if it's working. If not you may need to have it rebuilt with a new circuit board - cost me BIG bucks $1000.00 Aus. Next time it goes (and I'm informed IT WILL) I'm going to dial OFF, remove the bolt and disconnect the manual lever from the servo and yank at it manually.

If you CAN hear it whirring away and yet feel no heat - then I'd say it's popped the rod off........ per Lee's post. Cost a buck fifty for a can of WD40.

RJM3 · 09-25-2002, 11:28 AM

check past threads there is some good troubleshooting even down to the circuit board rebuild...regards jer

Wil Ferch · 09-28-2002, 01:39 PM

Guys:

Thanks for the advice...the servo motor works. I've gone further and found:

- yep... the actuation rod popped off at the back of the unit, not where it attaches to the lever that directly moves the heater cables which is closer up front near the handbrake pivot.

Upon further investigation, the ball and socket joint is broken at the back end. The ball ( steel) is OK...the cup or socket that screws on the end of the rod is a cheap plastic ( ! ) and it's built to have a clasp on its end.. that tightens the socket around the ball. One assumes that you engage the socket over the ball, and then snap this clasp to "tighten" the cup. Hard to describe in words, but once you're in there you'll see.
Question: now that the actuation rod is off, I tried to move the pivoting lever that actuates the heater cables directly...and boy is it stiff ! It seems I have no binding anywhere in the system, so how do I know if this is " normal" stiffness. My point ? If this is abnormal stiffness...I'll still need to clean / lube / repair the cables...or other things... somewhere. Any quick test for this? I'll bet that that the cup failed either because of the cheap design...or that the stiffness was too much and caused the socket to fail.
---Wil Ferch

john walker's workshop · 09-28-2002, 01:50 PM

the plastic ball sockets have been redesigned. they no longer have the locking clip on the end. the new ones take some effort to pop on, but they don't come off.

Wil Ferch · 10-14-2002, 05:26 PM

Bump: ....
How can I guage whether the force requird to manually move the pivoting lever ( near the handbrake that attches to the heater flap cables below...) is too much?
I'm ready to re-attach the popped off rod, and all seems fine, but the force required to move the heater cables seems very, very stiff. Normal?
--Wil Ferch

LeeH · 10-14-2002, 07:53 PM

Wil,

When I first started working on my system I could barely move the cable by hand. After hitting both end of the cables and the flappers with WD40 the movement was easier, but still very stiff. I repeatedly worked the cables back and forth and it got slightly easier, but they never moved easily.

I found my original post with the same question you have. Several people report that stiff is normal (no jokes please!).

Question for those who have worked on their automatic heating control...

Lee

Guy Chiattello · 10-14-2002, 08:42 PM

My auto heater control went out yesterday. I took it apart this evening and found that the small arm that connects the servo and the heater control lever was off on the servo side. The plastic connector was broken. I will try to find one on Pelican parts tomorrow and replace. As I checked the thread on the automatic heater control this seems to be a common problem.

Guy Chiattello
1982 SC coupe

jlex · jlex's Garage

My '85 had the exact same problem when I bought it. Broken connector going to the servo arm. I used a 12 gauge piece of copper wire to replace the connecting rod. Have been using it that way for 4 years with no problems.
regards,
jlex.

Wil Ferch · 10-15-2002, 05:21 AM

Lee and others:
Thanks for the reply and guiding me to the old threads. It seems stiff action is fairly normal. I'll go through the system one more time ( relube, etc...although all seems fine)..and then re-attach. I'll report if more things pop up.
---Wil Ferch

jmohn · jmohn's Garage

Quote:

Originally posted by Wil Ferch
Bump: ....
How can I guage whether the force requird to manually move the pivoting lever ( near the handbrake that attches to the heater flap cables below...) is too much?
I'm ready to re-attach the popped off rod, and all seems fine, but the force required to move the heater cables seems very, very stiff. Normal?
--Wil Ferch

Hi Wil,

I just fixed a broken heater control cable on my SC a week ago (manual control), so I can tell you that the cable should not feel very stiff to move. I lubed the guide tube (WD 40) before I inserted the new control cable, and once fully in place I could move the cable with just finger grip (of course I had to "grip" it pretty good). The old cable did have some build-up of sticky old residual lube, so I flushed the guide tube liberally with WD 40 which, hopefully, cleaned the old crud out of it.

Jerry M
'78 SC

Wil Ferch · 10-16-2002, 07:41 AM

Hi:
Thanks...but this is difficult to restate in cyber space.

For those with auto heat..once the control box is removed and the the control rod ( with end-cups) is removed...you're facing a rather small pivoting lever next to the hand brake. The lower portion of this lever goes into the tunnel,. and you can see a cable that attaches to the lower point of this arm. I guess it ultimately connects to TWO cables ( one for each side of the car), but all I can see is one cable below attached to the arm...pretty thick too if I can recall correctly..like a wire from a clothes hanger.

Anyway...with the cupped-control arm removed, as I try to move this pivoting lever back and forth...the force seems incredibly high, even though I can easily move the heater flaps ( manually) at the hater boxes under the car. Either this is "normal"...or there is binding of the individual cables to either ( or both) of the heater flapper boxes.

Not wishing to beat this...just trying for clarity of original question.

--Wil Ferch

Wil Ferch · 10-16-2002, 07:44 AM

Hi:
Thanks...but this is difficult to restate in cyber space.

For those with auto heat.....you're facing a rather small pivoting lever next to the hand brake. The lower portion of this lever goes into the tunnel,. and you can see a cable that attaches to the lower point of this arm. The cupped control rod attaches to the top of the arm. I guess the bottom ultimately connects to TWO cables ( one for each side of the car), but all I can see is one, fat, cable below attached to the bottom of the arm..

Anyway...with the cupped-control rod removed, as I try to move this pivoting lever back and forth...the force seems incredibly high, even though I can easily move the heater flaps ( manually) at the hater boxes under the car. Either this is "normal"...or there is binding of the individual cables to either ( or both) of the heater flapper boxes.

Not wishing to beat this...just trying for clarity of original question.

--Wil Ferch

jmohn · jmohn's Garage

I think you described it very well, Wil. It's now clear to me; and it's also clear to me I can't be of any assistance with my description of the manual control cable, sorry. However I still see no reason why that cable (or cables) or lever should be difficult to move. On yours the auto-heat moves the cable by means of a small servo motor, correct? So there would be no need to have the mechanism held by friction (there are friction washers on the levers of the manual version), the motor will hold the cable at whatever position it stops at, it wouldn't tend to "drift" off position like the manual levers could.

I hope someone who has diagnosed this and fixed it will jump in with a solution.

Good luck,

Jerry M
'78 SC

APKhaos · 10-16-2002, 02:02 PM

Hi Will - sorry I missed this thread earlier, but you are on the right track!

The actuating lever drives a single cable, which in turn pulls a cable joining the two flapper valves - one each end of the second cable. The force at the actuating lever was higher than I liked. Even after lubricating the flappers and cables, it took a solid push to move it. This seems to be normal.

JW is right - there is an upgraded servo rod with better ball joint sockets. I actually repaired my old one, which had failed at one end like yours. Used two layers of heatshrink tubing, which I figured would have enough strength and flex to work as an interim until I found one of the newer rods.

Guess you know the next part - the repaired rod is still working fine two years later!

Wil Ferch · 10-16-2002, 03:22 PM

Gentlemen:
Thank you all.... for bearing with me on this....
John Walker's shop advised of the upgraded cup/rod. The old design has a clasp on the end of the ball, the new design does not. I copied the princple of the new design by using JB weld on the clasp ends of both cups...the one that failed and the other one that didn't. Both have JB weld on ( "in"..."around"...) the clasp.
We'll see how long it lasts !!
Thanks...
-Wil Ferch

Guy Chiattello · 10-17-2002, 05:58 AM

John Walker gave me the part number for the automatic heater servo rod ends. It is part # 999 168 021 40. These are the same ends that are used for the electric door lock rods.

Guy Chiattello
82 SC Black Coupe

10-19-2002, 03:57 AM

What's the actual control mechanism for the engine compartment fan. i.e. when does it come on and shut off?
I've looked at some past posts on this and seen a couple of things mentioned and would like to know for certain when it's supposed to be on so I can troubleshoot whether I have a fan problem or a control problem.
Thanks,