Please explain the climate control on 79
Thread Starter
Racer
Joined: Nov 2008
Posts: 469
Likes: 0
From: Tallinn (Estonia)
Please explain the climate control on 79
Hi!
I haven't received any of the manuals yet for my 79 and I've been wondering how the climate control panel is supposed to work. There are several positions on it like HEAT, DEF etc. When I have the blower motor set to Max and I fiddle around with the upper lever, I can hear a pretty loud relay sound coming from the front. But whatever I do with the lever, it doesn't seem to change the air direction like on the newer cars (feet, window, face...). The temperature selector works perfectly. How is it supposed to work when selecting the different settings? Thanks!
I haven't received any of the manuals yet for my 79 and I've been wondering how the climate control panel is supposed to work. There are several positions on it like HEAT, DEF etc. When I have the blower motor set to Max and I fiddle around with the upper lever, I can hear a pretty loud relay sound coming from the front. But whatever I do with the lever, it doesn't seem to change the air direction like on the newer cars (feet, window, face...). The temperature selector works perfectly. How is it supposed to work when selecting the different settings? Thanks!
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I think you're hearing the A/C compressor. The compressor should run when the selector is on defrost as it aids in removing humidity from the air so your glass de-fogs quickly and easily.
NCM Grand Opening Veteran
Joined: Sep 2005
Posts: 20,979
Likes: 384
From: South of giving a damn
St. Jude Donor '11, '17
Hi!
I haven't received any of the manuals yet for my 79 and I've been wondering how the climate control panel is supposed to work. There are several positions on it like HEAT, DEF etc. When I have the blower motor set to Max and I fiddle around with the upper lever, I can hear a pretty loud relay sound coming from the front. But whatever I do with the lever, it doesn't seem to change the air direction like on the newer cars (feet, window, face...). The temperature selector works perfectly. How is it supposed to work when selecting the different settings? Thanks!
I haven't received any of the manuals yet for my 79 and I've been wondering how the climate control panel is supposed to work. There are several positions on it like HEAT, DEF etc. When I have the blower motor set to Max and I fiddle around with the upper lever, I can hear a pretty loud relay sound coming from the front. But whatever I do with the lever, it doesn't seem to change the air direction like on the newer cars (feet, window, face...). The temperature selector works perfectly. How is it supposed to work when selecting the different settings? Thanks!
Thread Starter
Racer
Joined: Nov 2008
Posts: 469
Likes: 0
From: Tallinn (Estonia)
I see. The relay knock might be the A/C relay but my compressor has the belt removed so I cannot see it rotating.
I never thought the climate system is vacuum driven. The headlights come up and close perfectly so it seems like the issue is somewhere near the climate control. I checked today and I can feel air coming only through the foot vents, nothing from the side, center console or window vents. And it doesn't matter where the mode selector is set to.
I suppose reaching the A/C system is quite hard? What has to be removed?
I never thought the climate system is vacuum driven. The headlights come up and close perfectly so it seems like the issue is somewhere near the climate control. I checked today and I can feel air coming only through the foot vents, nothing from the side, center console or window vents. And it doesn't matter where the mode selector is set to.
I suppose reaching the A/C system is quite hard? What has to be removed?
Melting Slicks
Joined: Jun 2005
Posts: 2,938
Likes: 2
From: Arkansas
Mine's doing the same thing, I even installed all new hoses and lines....haven't had a chance to trouble shoot it yet.
Here is a diagram of the routing of the climate vacuum lines. A good place to start is make sure the main source is hooked to the engine intake, it routes through the firewall and to the selector switch in the console.
Here is a diagram of the routing of the climate vacuum lines. A good place to start is make sure the main source is hooked to the engine intake, it routes through the firewall and to the selector switch in the console.
Thread Starter
Racer
Joined: Nov 2008
Posts: 469
Likes: 0
From: Tallinn (Estonia)
I'm digging out this old thread of mine because I'm now getting ready to fix the A/C system, didn't have time before.
There is a loose hose under the hood that seems like a vacuum hose:
And it comes out through the firewall from a place like this:
At least out from the firewall the hose seems green but it's currently quite complicated for me to read from the diagram where it's exactly supposed to go. Where should I find the source hose that has to be hooked to the intake?
There is a loose hose under the hood that seems like a vacuum hose:
And it comes out through the firewall from a place like this:
At least out from the firewall the hose seems green but it's currently quite complicated for me to read from the diagram where it's exactly supposed to go. Where should I find the source hose that has to be hooked to the intake?
Burning Brakes
Joined: Jul 2007
Posts: 1,167
Likes: 284
From: Springfield MA
St. Jude Donor '10-'11-'12, '19, '21
With the car running, switch from defrost to heat. Can you feel the air at the top of the dash?(middle of the winshield vent on dash)
If you feel the change from the defroster vent to the floor vent your system is working properly. If not, you need to repair or replace the unit on the console. ( I just replace mine and my heater/defroster works just fine now).
I don't think the a/c is your problem. Good Luck!
Dave
If you feel the change from the defroster vent to the floor vent your system is working properly. If not, you need to repair or replace the unit on the console. ( I just replace mine and my heater/defroster works just fine now).
I don't think the a/c is your problem. Good Luck!
Dave
Burning Brakes
Joined: Apr 2008
Posts: 945
Likes: 1
When you switch from mode to mode be sure to give the system a few seconds to respond and be sure the car is running. As mentioned, make sure the vacuum is connected. There are two doors in the distribution box. One is the temp door and the other is the air diverter door. When you change modes a big flap changes position to direct the air down, up or both. The diverter door could be stuck in one position. The door is operated by a vacuum valve that operates a mechanical lever. Take a look on the firewall where the passenger's left foot would be and you should see a vacuum valve. Operate the mode lever and see if the vacuum valve is moving the mechanical lever. If not, give the box a good rap to see if you can free it up. If not disconnect the vacuum line, operate the mode lever and see if you have vacuum.
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Instructor
Joined: Jul 2008
Posts: 123
Likes: 0
From: Allentown PA
That first picture you show looks like the black vacuum line that is supposed to be connected to a vacuum source, likely from the intake manifold behind the carb. I found mine disconnected, I hooked it back up and the air inside the car was able to come out of the different ducts. Look at that diagram posted by CorvetteDude, there is a black vacuum line that passes through the firewall into the engine compartment and is labeled 'to source', that is the line I am talking about. Good luck. Btw, you might want to check that white line and make sure it still goes to your heater valve while you are at it.
Thread Starter
Racer
Joined: Nov 2008
Posts: 469
Likes: 0
From: Tallinn (Estonia)
Woohooo! FIXED!
I really thought this is going to be one of the most complicated repairs. However, today I firstly figured out that the broken hose was actually black and the green one in the photo above was something else. I also found the other part of the broken hose, it was really well hidden and it was connected to the hose that came out of the intake manifold behind the carb. I inspected the two hoses and it was very clear that it had just broken apart. The hose is very stiff and plastic-like. I drove to a US car parts store, they gave me a piece of larger hose for free and I connected the black hose together. Works like a charm now! I hope I can now enjoy defogging the windshield during those colder Spring days
The only thing not working in the climate system now is the A/C compressor because the belt has been removed and I suspect the compressor might be bad. We checked and there is still refrigerant pressure in the pipes so hopefully there are no leaks. I don't know if I even want to fix the compressor right now because should we get some warm days during Summer, I can take the t-tops off instead.
Here's a photo of those two pipes broken:
I just love working on this car. It's all simple enough for a normal person to understand and it's such an awesome feeling after having fixed an issue.
I really thought this is going to be one of the most complicated repairs. However, today I firstly figured out that the broken hose was actually black and the green one in the photo above was something else. I also found the other part of the broken hose, it was really well hidden and it was connected to the hose that came out of the intake manifold behind the carb. I inspected the two hoses and it was very clear that it had just broken apart. The hose is very stiff and plastic-like. I drove to a US car parts store, they gave me a piece of larger hose for free and I connected the black hose together. Works like a charm now! I hope I can now enjoy defogging the windshield during those colder Spring days
The only thing not working in the climate system now is the A/C compressor because the belt has been removed and I suspect the compressor might be bad. We checked and there is still refrigerant pressure in the pipes so hopefully there are no leaks. I don't know if I even want to fix the compressor right now because should we get some warm days during Summer, I can take the t-tops off instead.
Here's a photo of those two pipes broken:
I just love working on this car. It's all simple enough for a normal person to understand and it's such an awesome feeling after having fixed an issue.
Burning Brakes
Joined: Apr 2008
Posts: 945
Likes: 1
In your last pic it almost looks like a kink in the line where the small hose inserts into the short larger hose. Heat from the engine and years of use causes the rubber to harder so check all your underhood hoses.
Your compressor belt is probably off because the compressor is frozen. If you put a belt on and the compressor won't turn when the clutch is engaged and just squeels you probably have a bad compressor. Also note that if you have low system pressure the high pressure switch in the compressor hose near the compressor will stay off and not let the compressor run.
With limited experience with A/C be very carful messing with the system under the hood as it is under high pressure. If you decide you want to tackle the A/C in the spring get help from your forum buddies and have the system discharged by a professional shop before you open the system or take any parts off including hoses. The heater stuff is o.k. but the A/C stuff is tricky.
Your compressor belt is probably off because the compressor is frozen. If you put a belt on and the compressor won't turn when the clutch is engaged and just squeels you probably have a bad compressor. Also note that if you have low system pressure the high pressure switch in the compressor hose near the compressor will stay off and not let the compressor run.
With limited experience with A/C be very carful messing with the system under the hood as it is under high pressure. If you decide you want to tackle the A/C in the spring get help from your forum buddies and have the system discharged by a professional shop before you open the system or take any parts off including hoses. The heater stuff is o.k. but the A/C stuff is tricky.
