someone972

iTrader: (2)

Hello, so my heater control valve has been disconnected, and I'm not sure where the line that's supposed to hook up to it is. There is one line that is disconnected near the firewall, but it's very short. Anyone have any pictures or know where it connects?

This is on a 1991 Firebird Formula 5.0L TPI.

For reference I'm talking about the small connection on the top of this part:


And this is the line that is disconnected:

jermdm

From the pic you posted, the short line with the rubber vacuum line is for the HVAC. I have posted pics of my car to show you how its hooked up. There should be 2 plastic hard lines coming out of the same harness. You already have 1 so there should be another in the same spot coming out of the wire harness. 1 line is a vacuum supply line for the HVAC controller. This will allow you to change from floor to vent, etc. Does your HVAC controller make a hissing sound when moving the HVAC mode slider? The other plastic hard line will be for the heater control valve that you have pictured. Looking at your pic, I see your check valve has a broken off port. That's the piece that has the right angle rubber piece going to a tan looking plastic hard line. That tan line is going to another rubber vacuum line which should go to the vacuum ball reservoir and also to the cruise control servo. You can see the check valve I my pics and how it should be hooked up. Need more help, let me know. Hope this helps out.

someone972

iTrader: (2)

That certainly helps! I looked at it again today and there is a second tube coming out of the harness, which connects up to a vacuum line that goes down somewhere in the firewall. That same vacuum line also is attached to the tan line going to the check valve. I guess that means that the line pictured above must go to the heater control valve. You mentioned that the check valve goes to the cruise control servo, but it doesn't look like my car has cruise control, so is there still somewhere it hooks up?

jermdm

Since your car doesn't have cruise, you will still have the vacuum line going to the vacuum ball reservoir located in the driver side front fender. I will be mounted under the charcoal canister. This allows you to keep floor or vent position when under heavy acceleration. If the reservoir isn't hooked up, the HVAC will change to the defroster position under heavy acceleration then change back to floor or vent(which ever is selected)when you let off the gas. The check valve is a 1 way valve that keeps the vacuum in the reservoir, HVAC controller and cruise servo(if you had it). I can see that the other black plastic line is going to the rubber line behind the distributer that the tan line is also going to. It should be just fine to keep it that way since it's after the check valve, which is where you want it. Your other black plastic line with the rubber hose should be the line that goes to the heater control valve. Just run some longer line to the valve. Way you find out if its working is to turn on the heater, select floor or another position and see if you get vacuum on that line. Turn the heater off and there should be no vacuum. Could be vice versa. Not forsure.