I have a 88 pickup 22RE 4WD. The temperature control lever (slides from blue to red) will not stay all the way on red. I can push it over and hold it, and the air gets a lot warmer, but once I stop holding it, it goes back to about midway and the air cools down some. Will this be something to do with the cables? I have done searches, and can’t find what I’m looking for. Thanks in advance for the information.

That lever should connect directly to the heater control valve on the firewall. Have you looked under the hood to see if the valve is fully open when you move the lever to full heat?

Thanks for the information. I’ll check under the hood this afternoon. I was hoping it’s something simple, I just didn’t know what to look for. This helps a bunch.

Okay, so I looked at the valve under the hood. I can move the cable in and out with pliers, and can open and close the valve with my hand. But once I re-connect the cable and move the control on the dash, it doesn’t really move the valve. Maybe a very little. Seems like the cable may be in a bind somewhere. Guess I’ll have to pull the dash and see what’s going on?

An interesting thing happened to me the other day. I tried to change my flap setting to defrost and my heat level to full cool. Neither lever would move much and the knobs kind of went sideways when I tried. I popped the front panel off and a white clip fell out. I went ahead and pulled the control panel loose and both of the levers were loose at the pivot mount. Turned out that clip holds both of them in place allowing them to pivot. It’s a two piece snap together clip. 1 goes over top of the lever mount and 1 goes on the bottom and clips in to place. I opted to just drop in a screw and washer from the top and tightened it down with a nut over the original bottom clip. Worth checking out if you haven’t figured this out yet. My truck has AC so your setup may vary a bit if you do not.

I’ll try to edit with a picture when I get back to the garage.