1972 Plymouth RR --> HEATER NOT WORKING

[zextrot]

What is the most common problem when a heater doesn't work? The control switch? Where can i get a replacement?

 

[jessipup]

With the heater on and the car warmed up feel the hoses before and afterthe valve and on the return. Valve shut warm to vlv cool elsewhere. Vlv open warn before valve and after vlv, may or may not be warm on return but sooner or later the return should warm up if the heater core is not plugged. There is a start

 

[dangina]

thermostat, heatercore then controls i would look at in that order^the advice above is a good quick way to check if its the heater core

 

[YY1]

I'm replacing my heater control valve now.

Rusted shut, blocking flow to heater core.

I bypassed it using 4" lengths of 1/2 copper tube from Home depot, and it worked "all the time".

Valve was obviously not opening when cable moved.

 

[zextrot]

I could use a diagram identifying all the heater parts and their location. Anybody got that? I'm also having trouble finding heater parts online.

 

[YY1]

Folow the heater hoses- about a foot from where they go into the firewall at the heater core, there will be an inline valve mounted on the pass side fender. If you have a/c, both lines will go through metal tubes, but only one will have a valve. If you don't have a/c, only one line will be spliced by the valve. (OK, that's 73/74, but 71/72 should be similar).

The valve will also have a cable attached, that goes through the firewall to the temp slide control in the dash.

Look closely at the valve to check for obvious thick rust.

With the hood open, look at the valve and move the slide lever. Does the cable and actuator arm move?

I'd also unhook the cable from the actuator arm, and see what the motion ov the valve feels like.
Is it smooth? Can you see the plunger moving? Or is it very stiff with no movement?

If any of these things causes concern, I'd disconnect the hoses, unbolt the valve, and have a look inside to see if it actually opens when the actuator arm is manually moved.

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Rock auto has a valve that is not 100% correct for 73, but will work- $50.

It looks like the one I got from ebay. I had to drill one hole in it, and I reused the portion of the old mount that comes apart.
Had to tap the holes and find bolts, but smaller bolts and nuts waould have worked.
Also part of the new mount is too long. Doesn't affect operation, but I may trim it for better looks.

Don't know if it's correct for 72, but the correct for 73 ones I was able to locate were $125-$300. No thanks.

Advance also listed one for $57.

 

[zextrot]

thank you. if you have a photo of these lines or the valve, etc, that would be most appreciated!!

 

[YY1]

Here's the new one in place but not hooked up.

Note the heater core hoses bent up out of the way, and the copper tube as a temporary loop bypass. (also note the original from when the car was new Mopar logo heater hoses!!)

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Here's the new one and the old one side by side.

Not the same, but works.

Black line on new one is where I'm thinking of cutting it.

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Um, they aren't vacuum operated for 72 are they?

 

[zextrot]

i'm not sure yet on whether it's vacuum operated - i was wondering the same thing. i will let you know when i find out though. thanks for the photos!

 

[RJS]

Not knowing whether you have A/C or not is one problem, not knowing what engine is another.
Here is a picture of a bigblock 72 setup.
No heater control valve is used.
With car warmed up is one heater hose warmer than the other? If so your heater core is clogged.

 

[zextrot]

That pic is most helpful. I have a 72 with a 400. That's right, I don't have valves. I will check if one hose is warmer than the other. I'm also going to check to see if the control switch has juice going to and from it. There's also a resistor to check, as well as the core and blower.
On another note, i would REALLY like to see photos of where all the vacuum lines go. The air grabber has its own set of vac lines, and i have a charcoal canister as well.

 

[RJS]

View attachment 4047495-AIRGRABBERWHOLE1Model%281%29.pdfView attachment 4047496-AIRGRABBERWHOLE2Model%281%29.pdfView attachment 98435If your asking about airgrabber lines here you go:

 

[zextrot]

THANK YOU!!!
Yes, i needed those badly. I'm also needing to know if the heater on my 72 RR is operated by vac lines as well?

 

[72RoadrunnerGTX]

If you have a non-A/C car without the Strato-Vent option, the heater box is cable controlled, no vacuum actuated functions. The position of the firewall heater core hose connections will be as pictured above and will not have a water valve in the engine compartment. Here is the wiring diagram from the FSM for the non A/C blower circuit. Power feed (C1 14BK*, black 14ga wire with a trace) originates at the fuse panel. Should have a fuse labeled “heat-A/C”; check that first then move on the blower switch, from there to the resister pack. Some common issues are overheated connections however with no blower function at all I’d be looking for issues common to all speeds, complete disconnections at the blower switch, resistor pack, disconnected blower motor ground, bad blower motor. Need I mention blown fuse?

Beginning around December ’71 production a bracket was added to the valve cover to hold the canister vapor lines up over the exhaust manifold on the big blocks.

 

[zextrot]

Looks like you answered my same question on both forums. Thanks again!

 

[72RoadrunnerGTX]

More on the canister connections;
On the 4-port one year only ’72 canister, all ports are clearly labeled. A line connects to the fuel tank vapor separator via a hardline at the inner fender, a line to the enclosed carb bowl vent on OE carbs, a purge line connects to a tee in the PCV hose, and the fourth is connected to a tee in the vacuum advance hose. Be sure to check the diaphragm on the purge control valve; tend to develop pin holes over all this time. The diaphragm cover with the small port un-snaps or just vacuum test it at the port with a hand pump.

 

[fatecaptured]

i have a 72 charger 440 w/ a/c. It does have the heater control valve like the one pictured in 72RoadrunnerGTX :

 

[72RoadrunnerGTX]

Yes, A/C cars have the valves, Non-A/C cars, without Strato-vent, as I understand is the case here, didn’t use a water flow temperature control valve, as pictured above.

 

[rrTor-Red]

My car has the same valve as pictured above in 72RoadrunnrtGtx. 71 RR FYI

 

[YY1]

Any progress since I bowed out?