I need to get my heat/defrost working and have been searching the forums but have some questions.

The blower motor appears to be working, but there is very little air coming out of any of the vents. Earlier this spring the defrost would take a good 15-20 minutes to clear the windshield, but air was just trickling out.

The truck used to have a/c, but the guts were already removed when I bought it. From the engine bay I can see at least 3 hoses that are cut at the firewall.

Also where is the heater core - should I replace this?

Appreciate any help. Cheers

 

You really need to take your duct-work out from under the dash and restore it. It's really not that hard to get out. Take all the plastic pieces and clean them out with a brush and soap and water. Tape all the joints (use metal duct tape) or use foam sealing tape. Make sure all the flaps work. The flaps will probably need their foam seals replaced. Clean the old foam seal off the flaps with a wire brush then use spray on headliner glue to put the new foam on. Clean all the debris from the cowl vents on both sides. Make sure your defrost duct is sealed tight and lined up. This will make a big difference in how your defrost and heat will work. This will only take a few hours. I always take the glove box out so that you can see the fasteners better.

 

Can someone help me out identifying what the circled items are for?

There are two hoses at the top cut off and there is a wire connector that isn't connected to anything.

There is also a hose near the bottom that has been cut off. Were these all for the air conditioner?

 

You must have had a aftermarket ac system in there because there is no big hole in there for the box.

 

You can see in this picture the a/c controls are adjacent to the glove box, separate from the heater controls. But I thought this is one of the factory setups for a/c systems for these years? The truck is a '76. Either way, do all three of these hoses and the wire clip go to an a/c system? I'm concerned with getting the heat functioning, not a/c.

 

I can't see them very well, but the top two circled hoses should be for freon and the bottom hose is just a drain to let water out of the a/c plastic box. If you aren't getting much air, you probably have a plugged up a/c system. Take out the plastic, remove the thing that has those two cut off hoses coming out and see if that helps output. Heater core is connected to the other two hoses coming out of the firewall down below the cut off hoses.

 

Air flow can be tricky when aftermarket AC added try to take it out and check for doors not opeing or closing as they should, check for water control valve if no heat,but radiator gets hot, good luck

 

another question - i am assuming the heat is supposed to blow out of the vents on the dash? I messed around with it this morning and it is actually blowing air out of the vents on the floor, but nothing out of the vents on the dash.

When I turn on the a/c, it blows air out of all vents on the dash, but the temperature cannot be controlled. It just blows outside air into the cab it seems.

I'll check for water control valve. The radiator/thermostat are brand new.

 

bump. is the heater supposed to blow out of all vents or only floor vents?

 

If I remember correctly, the heat will blow to the floor or windshield and the a/c will blow from the left, center and right dash vents.

 

The heat and A/C are 2 different systems with dealer AC. No your heat will only blow on the floor or defrost.

 

Alright well that makes sense then. As I said, the a/c still blows air out of the dash vents, but its just ambient temperature.

How difficult would it be to get the heat to blow air out of the dash vents?

I got the passenger side heat system apart and took a look, everything seems to be operating correctly. The defrost doesn't have a tight seal up on the dash but there isn't much air coming out anyway. The fan is working and it's blowing air, its just a small amount. Is the blower motor just going bad and not operating at full speed? It runs, but like I said its just barely blowing any air.

 

So I ended up taking it all out this afternoon. The dealer installed a/c under the dash was a pain in the *** as it blocks access to some of the screws around the heater fan. So I ripped it out as well and do not plan on re-installing it. Although, what parts are needed under the hood to get the a/c running again?

For the heater, the defrost just didn't have a tight seal and I hope sealing it will fix the issues. I am thinking I will take the dash vents and run the ductwork into the heater box so I have dash heat instead of only floor/defrost.

As for the low airflow issue, I am thinking this might be part of the problem:


However, while I have it apart, should I just go ahead and replace the heater core, fan and blower motor?????

Just some other pics:




And here is the a/c system that was there:

 

I think since it's apart and it shouldn't be real expensive, I'd replace the blower motor, the heater core, and try to clean it up in general.

 

The parts under the hood you need for the A/C would be the compressor, condensor, drier, and new hoses. You'll need a new expansion valve on that evaporator you took out from under the dash. You could most likely flush out the evaporator and it'd be ok to reuse.