How do I? ‘83 CJ7 Heat troubles

[BlueberryCJ]

Hey folks,
I picked up my first CJ7 and I’m in love, but our fair land of Mormons is starting to freeze, and need your advice.

With the heater set to blow hot air out of the vents (yes I did check, my air knob is only 1/2 out), I’m getting lukewarm at best air.

The coolant line from the intake manifold to the heater box is nice and toasty, and the line from there to the water pump is marginally cooler.

I can visually inspect and see the little doors and cables working, so what gives? Any advice?

 

[Belizean]

The cables can get pretty stiff pulling after decades. Maybe a little silicone spray or graphite. MTS makes quality replacements

 

[jzak]

Several years ago I unscrewed the passenger fresh air vent and reached in to pull out a metric ton of leaves and pine needles that were blocking the air flow. You may wanna give that a try. Also, those heater core hoses should both be hot, if they're properly circulating coolant. If they're just warm, then you maybe dealing with air in the system or some kind of obstruction. Sharing some pics would be helpful. Good Luck!

 

[jzak]

The cables can get pretty stiff pulling after decades. Maybe a little silicone spray or graphite. MTS makes quality replacements

Agreed. Spraying everything with Silacon Blaster would be a good first step.

 

[TSB8C]

Like "jzak" said, both coolant lines should be hot. If one of them is noticeably cooler than the other, sounds like coolant is not circulating through the heater core as it should. So while air flow could be an issue due to years of leaves/debris accumulating in the ducts, if you're getting airflow out the vents, that's not your problem - hot water flow is. The heater core may be partially clogged with rust/etc, reducing the flow of hot coolant through it. Of course your heater core is inside the plastic housing to the left of the fresh air vent (see pic from "jzak" above).

Now there's also a common mod you can do to improve the airflow in the system. That is replacing the blower motor with one from a Chevy Blazer. Here's a great write-up on doing that if you decide: Blower Motor Upgrade