Can a HVAC programmer for 94-99 be rebuilt?

[turbowrenchhead]

My heat stopped working a week ago. So I pulled my dash out and seen that there was no control for the vacuum controlled doors or the temp door. I found a used programmer at the local yard for $75. I put it in and it worked for a week. Now its dead again. Does anyone know somebody that rebuilds these?

[willwren]

Do you have manual controls, or electronic?

Have you verified you have good vacuum at the programmer? Are you certain 94-99 HVAC programmers are all compatible?


(never heard of anyone rebuilding these since I've been here way back in 2002)

[turbowrenchhead]

Its automatic temp control. From what I read they should be compatible from 94 a through 99

[enslow]

Is this what happened to your programmer?

http://www.imcool.com/articles/aircondi ... m_line.htm

[willwren]

Enslow, the locations of the components in that article are incorrect, and it's very misleading. The programmer and vacuum lines are not accessible through the glovebox, as the Bonneville glovebox is located higher in the dash.

The important thing to know right now is whether the temperature display is flashing for awhile on startup or not.

[enslow]

Willwren, if he's already replaced his programmer, it's logical to assume he already knows where it is on a Bonneville. I posted the article because it appears to be a common problem with programmers, and something to consider during diagnosis.

[willwren]

Enslow, the original poster isn't the only person that will ever read this topic. My disclaimer is intended for the person that doesn't know better. We don't need new members tearing their cars apart looking for parts that aren't in that location.

As far as programmers being a common problem, I would say that's not the case at all. Since my join date in 2002 on this Forum, I can't really think of more than one or two that had to be replaced.

99% of the time, it's a small component (airmix actuator), clogged evap core, Fan resister/module, or poor/lacking any vacuum.

[turbowrenchhead]

The nipples were fine on both programmers. I took my air nozzle and was able to blow air through the different lines. The used programmer I put in there functioned just fine for the first few days and then the temp on the head display starting flashing again and it wouldn't control the heat. I get 90 degrees out of the vents. I would have to think that its a faulty programmer. I know that you can not pull the glove box out to gain access to the programmer. I think however it can be replaced from the bottom. I will find out. The yard has another one and I'm going to try it.

[gmman]

don't know if you still need ideas regarding your hvac system problem(s). here is something for your consideration if you don't have it repaired.

as Will suggests, the airmix actuator (aa) is suspect. the usual problem with the aa is a cracked gear resulting in slippage on the motor shaft. as i understand your symptoms, you cannot control temperature. this can be a result of the cracked gear. to verify that this may be your problem, locate the aa and cycle temp. you should see steady movement of the rod and arm that move the temp door within the plenum.

the reason that you may see the blinking temp display has to do with the programmer detecting a fault in the system. as the aa attempts to move the temp door the large gear within the aa is also supposed to rotate a smaller gear that is dependent. the smaller gear in turn rotates a potentiometer whose output is fed back to the programmer to verify that the temp door has moved to the commanded position. if the programmer sees no movement (the value of resistance from the potentiometer does not change or is incorrect) it will activate the error indication (blinking temp display).

note that the programmer will direct air flow to windshield and floor in the event of this error.

the aa is approximately $60 from rock auto.

[Jrs3800]

Both the manual and auto control will snap this gear... Much like mine did to me...

[turbowrenchhead]

Is it possible to replace the airmix accutator without removing the dash?

[Jrs3800]

Yes with a thumb ratchet and very flexible hands... Expect to bleed...

[willwren]

With the Hvac programmer pulled out of the way, you can reach up there with one arm if you move the seat all the way to the rear and recline it, laying on your back in the footwell.

I can do it now from start to finish (start is when I go get the tools, finish is when it's all together and running) in 20 minutes. Your first time will take you 3-4 hours and will involve pain, frustration, and a bad attitude in general.

[turbowrenchhead]

I'm a ASE mechanic with 16 years of experience. I bet that I will do a little better then what you guys predict.

[willwren]

I have more experience than you by double the years working on cars without the certification, and am intimately familiar with every component location on my cars. I swap motors in 24 hours in my driveway. I've been known to tear one of my motors down nearly every winter. The airmix actuator (if it's your problem) is still a challenge. Don't underestimate it.

This is a unique experience that some people just can't do. It has next to nothing to do with experience or knowledge, and everything to do with blind work at arms reach, upside down, with patience and very fine finger dexterity. Many that have done it twice or more still take well over an hour.

My advantage is my size. I'm 5'9" and only 150 pounds. I cut my teeth working on F-4 Phantoms in very small areas most couldn't get to. I have no problem laying upside down in the footwell doing the work, and my right hand is slightly narrower than my left due to a pretty sever accident years ago. That hand also has fewer live nerves in certain areas, so that pain doesn't become a factor even if blood is.

This job is also absolutely impossible without the correct tools. Many thumb-socket adapters are too long, and may have to be modified.

[Jrs3800]

I agree... Don't under estimate that mean little actuator... Although I will say, At least its not a Nissan

[Mechanical Mike]

Sounds like it might be easier to just go ahead & remove the dash.

[willwren]

It's a matter of time to do the job. Removing the whole dash is quite an undertaking.

[Jrs3800]

Just have to fish your hand up in there... The job can be done.. Just have to contort at little..LOL

[turbowrenchhead]

I took the dash apart the first time to see what was going on inside, it was a pain. So now I know how it looks under there and I think that I can do it without removing it, I will. Its possible that the aa has a dead spot in the gears like talked about in this post. I will try another programmer, if I get the same results then I will replace the aa.