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Heater issues on 68 RS w/fac A/C

2K views 9 replies 7 participants last post by  Everett#2390 
#1 ·
No heat. Blower motor works but makes a squeak noise.
Levers appear to move fine, A/C works great as does defroster, just no heat.

Is there a heater control valve that should be in-line on the heater hose?

There is some sort of resistor on top of the A/C box under hood has a 3-prong plug that appears to be worn? What does this do if anything for heat?

Any help or suggestions would be great. Thanks
 
#2 ·
Adam, there is no water valve in the hoses by OE design, however, a PO (previous owner) may have added one, might check.

The cables, specifically, AIR TEMP, controls a door for bypassing the heater core.
You can follow/feel the cable ensuring the cable is hooked up, no kinks in it, or ensure the door does swing with the cable selection. You can remove the glovebox for a better view.

The three-prong connector is the resistor block for selecting the blower speed, high speed does not go through the block A squealing motor on yours may mean it is time for lubing the shaft bushings, kind of an impossibility unless the fender is off so you can remove the blower and drill a 1/8 inch hole in each end of the housing for an oil access. By going this far, might as well install a new motor and transfer the blower cage. Reasonable priced ones can be bought from your local NAPA store, take yours for comparision at time of purchase.
 
#4 ·
If you need to replace the heator core (sounds like you do), ...it pretty much has to come out. Short of taking everything out, you probably could take the 'inner' box out from under the dash Not the easiest to do, but it can be done. This won't get you access to the motor, ...but maybe you'll find another reason you have no heat (which may all be related to the core).

If you plan on hanging onto your car, ....I'd say it's worth investing into an Assembly Manual, ...and a Factory Service Manual.
 
#5 ·
Are the heater hoses as hot as the upper rad. hose? Do you have a thermostat in the engine
Where are the hoses hooked up to on the engine. Is the cooling system full.
 
#6 ·
If you are leaking your radiator just might be too low on fluid. If it’s too low, there isn't enough fluid to circulate through the heater, & therefore, NO HEAT. Changing the heater core under the dash is a really big hassle. Check to see if your radiator fluid is really low. Buy some aluminum power for plugging leaks at the auto store. Sometimes that stuff will fix your problem for a long time. So you might be able to fix the heater core at a more convenient time.
 
#7 ·
Change out the heater core:
1. Drain coolant, pull off heater hoses at core nipples and drain into a clean pan.
2. Remove the seven nuts from the engine side, these hold the inside box against the firewall.
3. open door and lay down on carpet/floor, a continuous sheet of plastic from the top of the toeboard (bottom of the heater box) to under the pass seat and from the top of the driveshaft tunnel out and over the rocker panel. This sheet will collect the leftover coolant for collection and easy clean-up.
4. Remove glovebox door and glovebox - gives you a better view of the job so you don't have to lay on the floor and look up.
5. Grab the top and bottom of the neck on the left side, just about at the junction of the pass floorboard and trans tunnel and pull the heater box breaking loose the seal, then pull the far pass side of the box and as pulling out the box, guide the box to help the core nipples through the hole in the firewall.
6. Once box is loose, lay box on plastic with core straight up.
7. Use a 5/16 socket and remove the clamp, then pull out the core.

The cables are just long enough you don't have disconnect them.

One of two choices, take old core to store and match up the best you can with new core, You might have to use alum spacers making up for the thickness for the clip to do its job in holding the core in place, or, take the old core to a rad shop and ask if they can clean and fix core - better idea.

Replacement is the reverse, but you have to be aware of the nipples through the firewall. Any hard push and nipple joint-to-tank cracks and leak has been born.
Once box is back into place and before going to engine side, ensure all the cables work and their function, read doors, work.

Don't let your pets drink the antifreeze.
Fill with coolant and check for leaks and operation.
Enjoy a cold adult beverage when done, maybe.
 
#8 ·
Everett, Are those instructions for a standard heater or for a car with A/C ? They are quite a bit different !

Here are a couple pics of an "inside" heater core box from an A/C car.



 
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