Help! Havc

[Marv02]

Ok let’s get started I have read other threads about what can cause my HAVC not to work correctly.
In my 1986 Vett
I did what other has written take the control head out of the dash clean the contacts check the solder points.
Remove the Vacuum Programmer and did the same.
Still not working kind of The fan motor runs the vents will switch from defrost to floor auto Ect but I not getting any heat the Heater control water valve under the hood is not switching over when put the car on heat the Heater door under the right side inside the car is not opening.
It did this before I took the heater controls out to clean them.
I put a new A/C compressor but have not had it charged yet I what to wait until I get the heating issue fixed.
I purchased the car not running and now getting back on the road I don’t know how long this problem has been going on.
The HAVC control head in the car lights up good when push any of the buttons it seems to work?
ANYONE HELP what do I look at next it an electronic heater A/C controller.
Do I need to buy new parts to get the HAVC system to work Which ones and where to get them.

 

[boomdriver]

its been my personal experience with the electronic a/c control that 75% of the time when there is a function issue, that the BCM or blower power module is bad. I've seen people go thru the entire system looking for "why" when that module has the ability to do just about anything regarding the a/c system. It can even run the fan when the key is in your pocket.

About $75 and can be ordered from most parts stores.

Heater...it will not respond unless the temp control is run up past the ambient temp. The elect control gets air temps from both in and outside the cabin to help it decide what to do with air mix. Try setting the temp to 90 and try the heater again.

 

[Marv02]

I put the temp on 90 still no go what is a BCM where is it.
Where is the Power module.
Like I said the blower motor works fine

 

[boomdriver]

blower control module is mounted in top of the evaporator. 2 plugs go to the top. 4 on one plug, then 2 on the next plug. it controls power to ALL the things in the system.

 

[Marv02]

I worked on the HAVC system more this morning and what I have came up with so far.
I have vacuum going to the Programmer Continues vacuum going thought the red output vacuum line that opens the Defrost door all other vacuum lines coming out of the programmer not working no vacuum.
The fan motor works all speeds, the Control panel in the car lights up fine and showing it switching everything over no trouble codes.
HELP
If I need parts as in a programmer where do I get one not someone else’s broken junk, I don’t need 2 junk parts.

 

[boomdriver]

programmers rarely fail, so you're probably going to have to accept a used piece. I have not seen them in parts list anywhere.
Everything that you describe to me, points to the power module.

When ANYTHING acts weird in the a/c system, or fails to act right, that module can cause it.
Test the compressor clutch circuit, the low pressure, hi-pressure and cycling switch to see if there are any clues there about power module performance.



There was also a thread not too long ago where someone posted the ohms of a bad module and a good one. Modules fail in any one of a doz ways and leave many things working with others not. This module is responsible for completing the ground path to just about all the system components. Everything always has power, its the ground that is open or closed. That tends to fool most folks. They see they have power, and figure the circuit is ok. Not.

Call J&D corvette in Ca for any of these used parts or 20th street auto parts in Phx. Both places have quality parts and a good reputation. 20th st is often cheaper.

 

[Rex S]

Have you checked the heat valve operation to be shure it actually opens and closes?

 

[Marv02]

I found a new programer not cheep but the old one was rusty I ohms chech couple of the resiters were not showing a closed loop and other spots with the same resiters showed good.

I jummped on the Programer they are hard to find trust me on this the seller has 1 more new in box.

 

[boomdriver]

it was rusty?

thats bad....I wonder how or why? That thing is mounted so that it should'nt ever get wet, because those little solenoids are very delicate. I hope its just from a hi humidity climate and not actual exposure to water.

I bet they are hard to find...I've never seen one advertised new. I have a spare that I bought used about 15 yrs ago. It stays in the box with the other 87 c-4 stuff thats not easy to find. Back around 1993 after LT models came out, I bout 2 of alot of things as spares knowing that vettes were evolving and parts would only be produced for 10 yrs.

 

[Marv02]

The car was sitting outside in a open fild for 7 years when I got a hold of it the weather stripping was shout.

The VIN plate is rusty under the windsheild.
The guy I got my new programer from has 1 more new one.

If this not it I try the power Mod next.

 

[Marv02]

Still not working

I installed a new in the box Programer and new in the box power control Mod.

Still not working doing the same as before I don't get it.

HELP

 

[John Robinson]

Next Idea

Somewere you will have this vacuum valve. This valve controls the vacuum for the heater and the cruise. Oh does the cruise work?

http://farm3.static.flickr.com/2115/2223853353_ddc2223653_b.jpg

http://farm1.static.flickr.com/105/290560320_79fb23d3ab_b.jpg

This is the location on my 93 but I understand that your model will have one also.

I would suggest that you get some new vacuum hose and replace all the lines. Those small plastic lines with age will become very brittle.

 

[RoyalViking]

Hi Marv,

My car sat outdoors for 4 years. After hearing about the rust inside the of the interior of your car sounds the condition sounds similar to mine. Have you taken a look at the fuse block for corrosion on the fuses? It may not relate to the problem you are having. However, I did not look at this until I began to have problems with charging and drivability. What I had found was the corrosion was causing resistance at the fuse and as a result the fuse clips were getting hot and had lost the spring tension to maintain contact with the fuses. I had to replace about 90% of the fuse clips before I was done. Don't bother trying to clean the contacts on the fuses, just replace them with new ones. Let me know if this helps or if you find the clips are failing.

 

[Marv02]

No the cruise not working yet.

Somewere you will have this vacuum valve. This valve controls the vacuum for the heater and the cruise. Oh does the cruise work?

http://farm3.static.flickr.com/2115/2223853353_ddc2223653_b.jpg

http://farm1.static.flickr.com/105/290560320_79fb23d3ab_b.jpg

This is the location on my 93 but I understand that your model will have one also.

I would suggest that you get some new vacuum hose and replace all the lines. Those small plastic lines with age will become very brittle.

 

[John Robinson]

Next Idea

No the cruise not working yet.

My money is on the vacuum valve.

Since the cruise is not working that is a symptom that the vacuum valve is not working. and remneber that it is tied into two things it controls. They are the heater and next the cruise

 

[Schrade]

I installed a new in the box Programer and new in the box power control Mod.

Still not working doing the same as before I don't get it.

HELP

I knew this before you plugged it in...

Spend no more cash until you get FSM from ebay. You HAVE TO do proper diagnostics per FSM, or else your $$ will flow from your wallet with NEVER a repair accomplished.

 

[Marv02]

I think his kid works at a dealership he mite get me the info I looking for.

I knew this before you plugged it in...

Spend no more cash until you get FSM from ebay. You HAVE TO do proper diagnostics per FSM, or else your $$ will flow from your wallet with NEVER a repair accomplished.

 

[Marv02]

I notice today the outside temp light is flashing what causing this.

 

[Schrade]

I notice today the outside temp light is flashing what causing this.

Flashing? $5 says it's flashing for diagnostic purposes, not a short or open circuit (although last time I ante'd up a wager on the boards here, I lost yUP). Another reason to drop bids on FSM...

 

[Marv02]

I taking FSM stands for Factory Service Manual.

Flashing? $5 says it's flashing for diagnostic purposes, not a short or open circuit (although last time I ante'd up a wager on the boards here, I lost yUP). Another reason to drop bids on FSM...