Heater blows heat when set all the way to "COLD"

[fastricky]

What is especially irksome is this is a newly installed and refurbished heater box (I am NOT pleased with the shop, let's leave it at that!) My guess is the lever that slides from COLD to HEAT is not going all the way to the COLD setting because the cable stretched? So if I removed the faceplate (this is a '72 so I don't have the fan lever only the thermostat on this panel), unscrewed the lever assembly is there a way to tighten the slack (assuming that is the issue) so the lever now will fully and correctly be in the COLD position? Or is my analysis wrong? I've never attempted this so I'm planning my attack from reading the info in the Articles section. 

[rms_sandiego]

The lever moves a bowden cable that connects to the heater valve on the right side of the wiper motor enclosure. There isn't any adjustment on the dash side, but you can loosen the fitting that the cable attaches on the heater valve side and get the dashboard lever where you want. 

[Schon '02]

If you’re asking about the cable adjustment, I assume you’ve never done it before. While it sounds easy, it is all blind left handed work with a 7mm wrench. It’s easy to see the heater valve, under the cowl from the passenger side. The cable is on the back side of the valve. If you have an inspection mirror, take a look at the back side to get a mental picture of the lever and cable attachment. Reach in and get a feel for the nut location on the lever, then get in there with your wrench to loosen the nut. Make sure the dash lever is in the full Cold position, then reach in to the heater valve and make sure that it is hard against the closed stop (should be pushed towards the back of the car). Then retighten the nut. If you’re still getting heat in the box, then something else is wrong (such as a leaking heater valve).

[fastricky]

This is great info, I'll try this in the morning and will report back ?

[roadhog0]

Also note that on later cars (not sure what year it changed) the valve has a hole in it to help keep coolant circulating so it doesn't stagnate in the heater core. This tends to mean you always get some warm air out of the heater box. Only way to stop it is close both Heat and Defrost slider.

[Mike Self]

Someone (you, perhaps???) has reinstalled the bell-crank (the lever to which the bowden cable attaches) incorrectly on the heater valve shaft.  It's easy to do as the shaft is square, allowing the lever to be attached in any of four locations. 

 

If the lever is currently facing towards the front of the car and you're getting heat on a cold setting, unbolt the lever from the valve (without disturbing the valve's setting) and move it so the lever faces the rear of the car. 

 

Alternatively, if someone on the FAQ can post a picture of the lever's location either at full hot or full cold, you'll have your answer.

 

And if you did it, don't feel badly.  The reason I know the above is because I did it too...

 

mike

[fastricky]

7 hours ago, Mike Self said:

Someone (you, perhaps???) has reinstalled the bell-crank (the lever to which the bowden cable attaches) incorrectly on the heater valve shaft.  It's easy to do as the shaft is square, allowing the lever to be attached in any of four locations. 

 

If the lever is currently facing towards the front of the car and you're getting heat on a cold setting, unbolt the lever from the valve (without disturbing the valve's setting) and move it so the lever faces the rear of the car. 

 

Alternatively, if someone on the FAQ can post a picture of the lever's location either at full hot or full cold, you'll have your answer.

 

And if you did it, don't feel badly.  The reason I know the above is because I did it too...

 

mike

 

I didn't do the work so that's one I didn't miff but here some more info: The system worked well right after the heater restoration but in recent weeks now has started to blow warm on the COLD setting. So that leads me to believe a cable has stretched or shifted so I'm thinking Schon's direction is the way to approach it. 

[NYNick]

Cable could be broken. Make sure it's actually operating the heater valve in the right cowl area outside the car when you move it.

Betcha it's broken. They are notorious for doing so.

[fastricky]

4 minutes ago, NYNick said:

Cable could be broken. Make sure it's actually operating the heater valve in the right cowl area outside the car when you move it.

Betcha it's broken. They are notorious for doing so.

 

Will do, what up Nick! 

[fastricky]

OK thinking this is beyond me... took a look under the cowl and all that is exposed is the back of the heater fan and of course the wiper motor and arms. My car has A/C so I assume this will require removing that console (PITA) to get to the matter? 

[lilmo]

3 hours ago, fastricky said:

OK thinking this is beyond me... took a look under the cowl and all that is exposed is the back of the heater fan and of course the wiper motor and arms. My car has A/C so I assume this will require removing that console (PITA) to get to the matter? 

Heater valve and cable connection is on passenger side of the fan.  The "guts" of the valve can break, too, causing the symptoms you describe. 

[NYNick]

Zoom in on this pic right under the right windshield wiper. in the open cowl area. You can just make out a hose with a small radiator hose clamp on it. That's the valve.

[Mike Self]

Coupla thoughts...

Before dismantling anything, have someone move the dash control while you observe the lever attached to the valve, to make sure (1) the cable is properly attached to the lever (2) the lever is moving and (3) it moves in approximately a 90 degree arc.  If it's moving properly per the above, then you can rule out the cable as the problem... a Good Thing as it means you probably won't have to remove the heater.  

 

I don't believe the cable can stretch enough so that it isn't moving the valve lever through its full arc.  So...next step is to make sure the valve itself is OK.  If it's the original valve on your roundie, the rotating part inside its housing is brass; the lever has a square hole that mates with a square boss on the rotating valve; later valves--and the ones you now buy new--have plastic rotating valves, thus the boss to which the steel lever attaches is also plastic.  The lever could be loose or the square boss may be rounded off so the lever doesn't do much when pulled/pushed by the cable.  To ascertain this you'll have to remove the valve and check it for proper operation.  

 

Let us know whatcha find...and if you have to remove the heater, I did a column on removing a heater from an air conditioned car without having to break the refrigerant hoses to do so...PM me if you need it; hope you don't!

 

mike

[fastricky]

2002FAQ does it again!

 

I found the valve with Nick's help and what I discovered is everything is functioning properly. But what I also discovered is when the thermostat lever is slid all the way to COLD the valve still had a bit further to travel to be fully closed. So I removed the faceplate and discovered the lever assembly could be loosened and moved to the right so the thermostat lever could move that extra little bit leftward to fully close the valve. Pretty confident this will solve the problem. 

 

I rewarded myself by looking into the trunk to diagnose a new fuel smell and found the fuel pump hose was slightly loose. Tightened that and am chuffed with two issues solved. 

[Mike Self]

1 hour ago, fastricky said:

But what I also discovered is when the thermostat lever is slid all the way to COLD the valve still had a bit further to travel to be fully closed.

You can also adjust this at the valve end, by loosening the pinch bolt on the lever, manually closing the valve by hand, then tightening the cable to the pinch bolt.

 

mike