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Heater Question


cpt_morgan

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Ok folks I have a 1977 280z. The PO removed the a/c system and now when you turn the heater on air does blow out of the vents but it never gets hot... I did a search and didn't really find a solution to this problem. Does anyone have any suggestions on what I should check/replace? I'd like to drive it sometimes when its raining or cold outside

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When he took the AC out he may have disconnected the cable to control the flow of coolant into the heater core. It is hard to get to if you don't have the dash out, but if you take the fan out there are three bolts holding it on two on the firewall and one under the dash by the small white box where all the wires hook up on the passenger side. If you take the fan assembly out you should be able to see it laying on your back. If you want to take your dash out that would work too. Do you feel any resistance when you move the hot-cold selector? also are your coolant lines from the engine hooked up to the firewall?

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When he took the AC out he may have disconnected the cable to control the flow of coolant into the heater core. It is hard to get to if you don't have the dash out, but if you take the fan out there are three bolts holding it on two on the firewall and one under the dash by the small white box where all the wires hook up on the passenger side. If you take the fan assembly out you should be able to see it laying on your back. If you want to take your dash out that would work too. Do you feel any resistance when you move the hot-cold selector? also are your coolant lines from the engine hooked up to the firewall?

 

Ok I took a quick look this evening at things...its raining and I don't have time to take the fan out and look up under the dash and all. I will try to do that this weekend. The hot/cold switch has resistance when you move it left to right. The air switch above it has little to no resistance when you move it left to right. It does give a little resistance when you move it all the way over to defrost beginning about an inch from the far right to all the way over. The 5/8 heater coolant lines are attached to the firewall from what I can tell.

 

I did find this however

 

post-10289-12723268094526_thumb.jpg

post-10289-12723268454963_thumb.jpg

 

There is a hose that goes from the intake by the cold start valve over to the area by the fuel filter. It has a plug in the end of the hose but there is a hard line right next to the fuel filter. Does this go here? Or is this something to do with the A/C.

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  • 1 year later...
  • 2 weeks later...

Is air coming out of the front vents? floor vents? or defroster vents?

 

Heat should only come out of the floor or defroster vents.

 

If air is coming out of the front vents when the air flow is set to heat/defrost then there is likely an issue with the vacuum lines under the dash.

 

 

 

In the picture you posted, I believe those lines went to the charcoal canister for emissions purposes. It's been a while since I have messed with the stock setup but that bracket that the plugged rubber hose is lying on, is where the charcoal canister used to be mounted.

 

 

 

and i just realized how old this thread is.... oh well. lol

Edited by 280zcar
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  • 7 months later...

This is the closest topic that i could find to the issue i'm having. but it didn't answer my question.

 

My fan works! but the air that comes out of the vent is ambient temp no matter what temp setting i have it set to. also the air doesn't move when i select defrost heat or cool. My question is if everything is hooked up right what could be causing this? are the switches vacuum controlled? The PO did tell my the Vacuum line for the AC that is supposed to be hooked up to the intake is bad and needs to be replaced. could this be why the controls don't work?

 

Once i get this figured out i will feel more comfortable about buying AC components to get the AC up and running.

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  • 2 weeks later...

The dash vents only supply A/C air, no heat. Heat only comes out at floor or defrost. If changing the mode switch doesn't change where air is coming out then you have a vacuum problem somewhere. The vacuum for the system enters via a port n the firewall near the heater hoses. Start there and work in. Verify that you have vacuum getting inside, then find the leak. It's probably not actuators if no modes change at all. Likely the main feed got nicked, or the selector switch crapped out.

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