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A/C blowing out wrong vents


2old2fit's Avatar
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05-18-03, 06:10 PM   #1  
A/C blowing out wrong vents

I have a 1988 Old 98 Regency with around 114,000 miles. When I turn on the Air Conditioner the air blows out through the defrost and heater vents. It did the same thing last summer on and off. When you turn the A/C on the air would always start out blowing out the defrost & heater vents then you could hear the damper "flip" and the air would come out of the right vents. Any suggestions to correct the problem? Does this require tearing apart the entire dash to get to the problem?

 
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05-19-03, 09:21 AM   #2  
Joe_F
Depends on the system it has. If it's a simple slide (non electronic system), the selector valve (if equipped) on the back of the A/C control is bad. If it's electronic, it's whatever controls the flapper door.

Time for a $25 Alldata.com subscription. That will give you good information.

 
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05-29-03, 06:16 PM   #3  
The A/C system is electronic. I have replaced both the Programmer and the Control Assembly. Still not getting air out of the A/C vents. I can apply vacuum to the Defrost/AC actuator and get the damper to close and work correctly. The main vacuum source also works (will hold a piece of paper in A/C mode).

The wires look fine as far as I can tell. Didn't see any loose or frayed wires. I checked the voltage at the programmer like the manual says to do. I barely get any reading at all in NORM mode. The manual says it is to be less than 1 volt. Well, how much less?? I barely get the needle to move off zero.

I have even tried putting a splice wire on the Grey/White wire directly from the Control Assembly to the Programmer. Still get the same readings and results.

Have also checked the purple wire voltage at the programmer. Get the same voltage readings as the Grey/White wire.

Any suggestions as to what to check or look at next?

 
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05-30-03, 01:21 AM   #4  
make sure your vacum lines are in good condition and not leaking under the hood going to the firewall just a small leak can cause this problem and still apply some vacum just not enough to switch the servo.
also how did you apply vacum with a hand held vacum pump?
did it hold vacum or bleed off.

 
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05-30-03, 04:55 AM   #5  
I was able to apply vacuum to the blue hose going to the actuator by merely sucking on it (like a straw). As far as the purple hose (vacuum source thru fire wall) I disconnected a coupler just before the hose goes into the programmer, ran the engine and the A/C to see if the main hose was in vacuum. Like I said earlier, there was enough vacuum to hold up a piece of paper (about 1" square). So there is "some vacuum". The part I still do not know is if there is any vacuum once it goes through the programmer. I have not attempted to disconnect the blue hose only from the programmer to see if there is vacuum where the hose connects to teh programmer.

 
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05-30-03, 05:58 AM   #6  
darrell McCoy
Pay particular attention to the hose where it connects to plastic nipples, these have a real nasty habit of splitting, a small crack in hose makes a big difference. I believe there is a plastic ball under the hood which is a vac reservoir, lots of heat in that engine area so check the hose that is attached to that thoroughly. Sometime those leaks are a real bear to find. A bad swx can also give problems, but I understand you did replace that control. Maybe to sort of get you by untill you pin point the problem, try switching controls to the mode you desire before turning blower on high. Less resistance on the "Flapper". Did this on an older GMC P/U till I found the problem.

 
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05-30-03, 06:50 PM   #7  
Is it possible to have a clogged vacuum reservoir? The system works fine if I by pass the vac reservoir and connect the hoses direct.

 
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05-30-03, 07:05 PM   #8  
darrell McCoy
I never ever saw one "clog" but have seen them cracked. See if it will hold air/vacuum. Check the small nipple also.

 
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05-31-03, 08:52 AM   #9  
I checked the reservoir for cracks and didn't find any.

Between the resevoir and the engine there is a little valve that will only allow "vacuum". On the backside of the valve is a hole. If I cover the hole with my fingertip, The A/C blows out the right vents. If I uncover the hole, the A/C will revert back to blowing out the defrost & heater vents. The hole is allowing too much outside air too be sucked into the engine, rather than getting air through the HVAC system. Is this valve supposed to have a hole on the back side in order to get more air into the system?

 
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05-31-03, 02:23 PM   #10  
darrell McCoy
I am somewhat of a loss with the valve you describe. I would only speculate it to be some type of check valve. Most I have seen, the hose runs from engine to canister, with a -T- configured fitting between and a hose running from that thru firewall to the dash controls. It I suppose could be mistaken for a valve as some have a round back. I cant think of a reason for it to have a hole.
The vac system cannot have any leaks else controls will not function properly. You may eventually need to go by a GM dealer, ask the parts or shop tech to tell you what it is or what the function is. They can show you a diagram of that underhood set up. It may have an internal diaphram or something of that nature that has failed. Perhaps you have found the culprit.

 
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05-31-03, 04:38 PM   #11  
Joe_F
Easiest way:

Go to any GM dealer and get a printout of the vacuum system for your A/C setup. The parts books have nice illustrations and part # callouts for these items.

Then, you'll know the part # and the name of the part in question. Shouldn't be but a couple of bucks. It is probably a check valve.

If you identify a Delco part # from the dealer's parts printouts it can be ordered from any auto parts store handling AC Delco product as well. You can also try www.acdelco.com as well.

 
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06-01-03, 06:18 AM   #12  
I stopped by the local auto parts store yesterday afternoon. They had the "check valve" in question. The hole on the backside of mine was actually an additional port that had broken off. They sold me the new two port check valve(as well as a cap to go over the 2nd port) for around $4. Put it on last night and everything works. Thanks for your assistance and patience with me in finding the problem.

 
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06-01-03, 06:28 AM   #13  
darrell McCoy
sometime without seeing the actual problem, takes a while. Glad you are back in business with your A/C problem. Good work.

 
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06-01-03, 11:30 AM   #14  
Joe_F
Good job! Glad to help.

 
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