Jmpsu791

Hello, I've done some looking around the boards, and via Google, but i can't seem to find anyone with the exact problem I'm having. Similar, but not quite. When i move the **** to vent, only cold air/ outside air comes in, and the fans don't seem to be blowing very hard.

When i turn it to heater it doesn't blow at all and there is no heat. it seeps out cold air. When i turn it on defrost, it blows cold air. When its on vent it hisses a little, and when its on heater is hisses like crazy.

When i move it to the AC options it doesn't hiss, and blows air out of the vents, ( albeit not cold, but i think that is because it needs recharged or something, I'm much more worried about the lack of heat).

So my question is ;is the Vacuum selector switch like many other people have noted.. or is it something else?

Also, is there a good place to buy one from? Napa's site lists it, but when you go to purchase it is discontinued, and i can't find one anywhere else, besides one place i have never really heard of before for almost double the price.

Any help would be greatly appreciated!

TreeFiddy

If it's hissing, sounds like the control valve. Was about to suggest a local vendor over here who had them, but apparently you guys already cleaned him out!

https://pontiworld.com.au/usgmsp/pro...274665c2b2b12e

Jmpsu791

Does anyone know where to get one of these? I've been looking and looking but to no avail.

ex-x-fire

Make sure the vacuum connections under the hood are good.
Are the heater hoses getting hot?
I've had one that was giving me trouble, so I took it apart & put alittle dielectric grease on the vacuum switch. This switch is in two halves that twist on each other to redirect vacuum.

Jmpsu791

So, I took it apart, and put the grease on it. It sealed a little better, but then since it was so cold a piece off of it snaped. So, I'm going to need a new one.

However, the heat also doesn't seem to be blowing all that hot any how. When i had the piece in, it was warm but not hot coming out of the defroster vent, but when i switched it to heater again, it didn't seem to come out of the vents. I checked the heater hoses, they are hot. The coolant is good. I'm just at a loss what to do. I mean the next step is clear, I need another one of those pieces.

FSTFBDY

iTrader: (33)

what year is your car? Have you looked on ebay or some of the venders like hawks , etc..
Ive had to remove the AC setup on my vert for my turbo setup. If my '92 one is the same I'd sell all the vac. lines and fitting i you need.

Jmpsu791

Its a 92 RS, and if you check the 2nd post in the thread, that link shows the part i need. It has been discontinued by GM as well. Let me know if you have that piece. I do believe the vacuum lines are good.. does anyone else know what might be causing the lack of heat? I'm going to check the thermostat tomorrow, and make sure there is no hiccups there.. but I'm just confused.

FSTFBDY

iTrader: (33)

get yourself a IR temp gun. just measure the inlet and outlet hose going to the heater core. that will tell you if you have circulation thru the heater core. If so move on to the next system of the blend door not switching and blowing all the air over the heater core.

a62belair

My heat problem was the lever under the hot/cold air door was broken. PO must of had someone kick up under the passenger side dash. That is where the (hot/cold) cable ends under the dash.

Jmpsu791

I just checked that, and it was fine. I sorta fixed the vacuum switch, ( it works for now, but before i put it all back together I'm going to put a new one in. )

However, none of it seems to be fixing it. The vacuum switch made it now so it blows somewhat warm air. Does anyone know where the vents that blow across the heater core are located and how to get to them? Maybe not all the air is getting blown across it?

The hoses get hot, the thermostat is opening. All of that good stuff. I'm thinking its the vents to the heater core, or the core itself?

Anyone else with any input? I don't have much expertise in this type of thing.. figures it would be the one thing wrong with it.

sonjaab

Are BOTH the heater hoses under the hood hot when the car is completely warmed up?
Can you hear or feel the temp control door move when you slide the temp control
**** from side to side?

Brando5641

iTrader: (-1)

That steel rod that actuates the blend door will sometimes get bent not allowing the door to fully seal off the path allowing non heated air to go around the heater core. If that is not it you are in need of a heater core. Mine is doing the same thing, it is full of crap and not allowing coolant to hardly flow threw it at all.

Jmpsu791

both the heater hoses are good. The door, while i cant' feel it move, when i move it from cold to hot, you can feel it go from colder to warmer air. I opened up the panel and looked at it, and i watch the rod move, it seemed to be in proper order.

FSTFBDY

iTrader: (33)

Id take off both heater hoses under the hood and stick a garden hose on one. Try and flush it out. See how much flow you get out of it. Then do it the other way also.

If flow is good both ways and its clear clean water you know its not clogged.
And a blend problem.

UNCLE TOM

iTrader: (1)

i would also like to know a source for the mode selector valve . anyone know ???

a62belair

I also had to remove my fan, and found a nest in the fan housing. Now I have lots of air flow. Maybe you have a nest in your fan or core?

Jessy Byrd

I have a 92 rs camaro and i just replaced mt thermostat and my radiator and my heater doesn't blow hot air both of my heater core hoses are hot when you feel them whats wrong? is it something with the blend door or what my thermostat is a 190 degree i think

FRMULA88

Replace the heater control valve, it's blown. Any auto parts store should have it or can get it.

it is a black disk with a vacuum hose attached to it. located on the passenger side of the engine. the supply hose for the heater core goes in one side and comes out the other. Normally When you move the lever to "heat" vacuum from the control head opens the valve to let engine coolant into the heater core. when the valve is blown vacuum cannot be applied so it stays shut the result is no heat.

Mine failed in 1995, it takes about 10 minutes to remove and replace it.

I often wonder if some of these posts are legit are all of you really so lacking in mechanical aptitude?

You can easily disconnect the vacuum line at the control valve and test the valve with a vacuum pump.
If the valve does not hold vacuum you have pinpointed the problem.

FRMULA88

$ 16.99 at autozone...

http://www.autozone.com/climate-cont...-control-valve

P/N 74805

Jessy Byrd

If my heater control valve is needed to be replaced wouldn't one of my heater hoses not be hot or no?

FRMULA88

IDK what sort of deductive reasoning this is?
Both heater hoses connect to it, look at the part.
The heater hoses use engine coolant and supply it to the heater core. if those hoses are cold.. your engine if off and cold too.


The control valve acts as a bypass, when you call for heat vacuum opens the valve to send hot coolant to the heater core. when it's off it's bypassed back to radiator.

If you did not have a valve to control the flow of coolant to the heater core, you would have no way to shut the heater on or off. but in this case because the valve is blown the heat is simply "off".

The hissing you hear is the blown diaphragm in the heater control valve. replace it and problem solved.

Jessy Byrd

Thanks