I have an 80 coupe and when I turn on the heat, the blower only blows from the floor. When I put it on vent or defroster, nothing happens.

I've been told the doors are stuck on the default position (Floor) and maybe have a vacuum problem.

Does anyone have any suggestions? If you do, what do I need to do to fix it?

A/C doesn't work either, but I will tackle that another day or is that tied into the problem too?

Anyway, I would appreciate any help.

 

Check the vacuum feed that runs from a tee off the main manifold vacuum source and runs behind the distributer to the firewall.Mine did the same thing and I found a broken vacuum line.

 

Yes, this is usually a vacuum issue. Try checking under the center console where your heater control is. There are several vacuum lines there, one may have pulled loose from the control. You may also want to check for a loose, broken or kinked vacuum line.

 

I'm dealing with the same problem. Just above the gas pedal and towards the passenger side is the vacuum actuator that contols the deflector doors. Out of the middle pointed down is the actuator arm that controls the door. If you pull it all the way down it will push the air out of the defroster vents. Mine has a vacuum leak somewhere because it moves back to it's rest position and blows air out of the floor. Not a permanent fix, but when I had to drive my car on cold mornings, I used a bent wire coat hanger to hold the actuator arm in the defrost position.

 

Pull the passenger side console carpet panel off, start her up and put your ear right next to the climate control. Listen for hissing - it will be obvious. Make sure the vacuum lines are all seated properly in the controller. Also, check to see if the retainer clip at the bottom of the actual controller has somhow broken or popped off. This $.25 part can cause your climate control system to do exactly what yours is doing - or not doing, as the case may be. Also, as other's have stated there is a vacuum line that runs from the enginer compartment back through the firewall - see if the plastic T-connector has quit on you or if it is crimped somehow.

As a side note, have you done any work under the hood or in the dash recently? It is real easy to knock a line loose while doing work on the car, especially installing a new radio or doing standard maintenance under the hood. Good Luck!!

 

I want to thank everyone who responded.

I check the bottom of the control last night by pulling the passenger side console carpet panel down and could see the control. Are the small hoses going to the control vacuum hoses? They look like electrical because they are so small.

If they are hoses, they go up in the dash and I can't follow them. Will I have to pull the dash out to check them?

 

Oh, the joys of vacuum operated controls.....
I removed the glove box liner from my corvette and it allowed lots of access to the area in question. Yes, if your 80 is like my 79, the vacuum hoses do go back there. The hoses are rather skinny and do look a lot like wires. It may also be that you have a bad heater control manifold, this is the switch under your center console that all of those vacuum hoses connect to, the same one that says heat defrost etc.. Good luck!

 

The easiest way to check is to find the vacuum line under the hood and test with a vacuum pump.If you can hold vacuum then start testing the different positions,if that all checks out your problem is under the hood.

 

Yes, those are the hoses. Before tearing apart your interior I would do a thorough check of the climate control switch in the center console as well as the vacuum hose connections under the hood that come through the firewall. I would be very surprised if the problem up under the dash. Not saying it isn't possible but I would try for the easier fix first since tearing apart the dash just plain sucks. Plan on a whole day of torture and inventing new four letter words if you have to go that route.

When you have the console carpet out start the car, put your head right by the control, and move the climate control lever that controls the A/C, Vent, Heat, etc. As you move the lever it should be changing the flow of the vacuum to the various components. It is a mechanical switch, so to speak, so as you move the lever it is changing the flow. Watch and listen. If you do not hear slight hissing as you move the lever while it changes modes there is a good chance you have no vacuum at all to the selector. If you hear exorbinant hissing you may have a leak at the switch. Look for any hoses that might have popped off the control. There is not a whole of lot stuff right there so it should be pretty simple to see. You'll notice the little hoses each fit into a rubber like socket. Just make sure all the hoses are seated well in those sockets. On the bottom of the control there should be a metal clip that is gray in color that is supposed to hold the whole thing together - can't miss it. It is at the bottom of the control, dead center with one flat side to it. It very easily can pop off and cause issues.

Under the hood check for vacuum leaks. I have found subtle vacuum leaks under the hood when I have the hood open, I stand outside the car by the driver's side, I reach in through the window and shut off the motor. In many cases you'll hear the hiss of a vacuum leak AFTER the motor is off since in effect the pressure is still there after the motor is off and it is bleeding off through the leak. I found two small leaks this way just two weeks ago. Anyway, that's my $.02 worth. Again, I would try all the easy stuff before ripping apart my dash.

Good luck!!!

 

I had the same thing on my 77. I am not sure it is the same as your 80. Mine has the controls that look like what is in every other chevy. It is different than the control that you roll. Anyway, Mine was in the vacum diverter valve. It is the vavle or control that directs the vacum to the different areas-defrost heat or vent. The lever moves it to the appropiate vacum sorce. Anyway, I took mine apart but broke the center stud that holds it together-more on that later- but inside there is a rubber gasket that looks like a circuit board only in rubber. When you move the lever it allows vacum to flow to the different control. I cleaned the rubber gasket thingie and both surfaces and then drilled the center stud out and used a small flat headed screw and nut to hold it together-it worked very well and fixed my problem. I would suggest you make sure you have vacum to the valve first and check with a vacum pump the various lines. If you can get the various outlets to work wit the pump and you have vacum to the valve then it is the control thingie. You can access it from the sides of the consol. It is very difficult to get a screw driver on it but I got mine out without removing the top of the consol. Hope this helps and you can follow it.

 

I think the correct name for the part is the blower control valve. It is a round part on the actual heater controls.

 

 

Thank you to everyone for the advice.

I will try and do everything suggested here today and will let everyone know if I get it fixed.

Thanks!

 

Many times the problem you reference (air only on the floor) is because this diverter valve breaks. It is fairly inexpensive from parts at the dealer.

 

My heater vacum lines have been bubba'd. On the firewall there is a grommet, right behind the trans dip stick with three lines coming through. One goes to a door under the right fender, one goes to the valve on the water line. Where does the third go? Also, do those lines go straight through, or are they pluggged into this grommet. I can't seem to get them to unplug from the grommet. Thanks......


(By the way, I found this thread through the search)

 

porta vaccume switch-----the solid black is the vaccume feed to the switch,,the rest are loads,i took the feed off and 1 by 1 tested it to each load using a plastic vaccume coulping,,in other words i took the vaccume feed and directly put it to 1 load at a time, its really pretty simple you can pick up a temp vaccume feed under the hood and start putting it to the loads,, if the accuators dont respond to a known live vaccume source,, they have to be replaced.....doc rebuild sells the accuators,,,my problem was e z ,,,the last owner pinched the vaccume feed installing the radio,,no vaccume ---no workie accuators!! here's a vaccume diagram that should help --- i color coded the lines as the tracers are on the vaccume lines-good luck and let me know if you need any more help,,,,carl---------------------------

 

This will be a good one for the archives!

 

They go straight through the grommet, they do not plug into it.

 

Thanks, saved me some head scratchin'!!!

 

I forgot to say this in my post, but the problem with my valve was that the lube had seemed to dried and "balled" up causing a bad seal between the two pieced of plastic. I lightly greased the seal when I put it back together and so far......... I wonder if these are still avaiable at Chevy?