When I first bought my Formula, the heat worked great. In fact, right before I bought it, I believe the heater core was replaced. Well, now the heat seems only to get lukewarm to warm. I am hoping there are some suggestions for easy things to check here....it's cold in New England in December!

Thanks in advance.

Dave

 

Thermostat? Heater bypass valve?

 

When was the last time you changed the anti-freeze? Are you sure it's topped off? If it's low then the air will get a little warmer as you drive, but no where near what it should be. Apeiron had some good suggestions too.

 

Ok, if I replace the t-stat, is there a particular temp version that our cars like better than others? And as for the bypass valve, how the heck do I test that?

 

What temperature does the temp gauge say? If it reads at the 1/4 mark, then yea, I would suspect thermostat. If it reads at normal op. temp, but you still have no heat, then I would suspect a blockage somewhere, be it in the hose, the valve, or at the heater core itself.

As for the thermostat, 195° is the factory temperature and my personal favorite for winter.

You can check the valve by watching it once you remove the heater hoses and switching the A/C to max (the internal door/valve should close).

 

The gauge has been reading at the 1/4 or less mark...I kind of thought maybe both that gauge and the oil pressure gauge were just dead, since both seemed to be reading "off" lately. But, maybe it is as you say, and is indicating a t-stat problem. I'll swap it out and see what happens. Thanks for the temp rating, too.

 

when i bought my truck (used) it had no thermostat (common practice in FL but I don't recommend it). In the winter it would only warm up to less than 1/4 on the temp guage unless I went more than about 50 miles. My heater performance sucked. I installed a new thermostat and it gets to operating temp within about 10 miles or so and the heater works great. most thermostats are set up so that if they fail, they fail in the open position. This is what you might be experiencing.

 

Broken vacume line to the heater bypass valve also can effect this.

 

That may be the case, but as I understand it, the default position for the hot water valve is open. Vacuum is used to hold it closed. Or, do I have that backward?

 

That is what I understand it to be. When you slide it to A/C Max, vacuum is applied and closes the valve.

In it's old age, the valve may get stuck in the closed position, however, that would not cause the engine to not heat up. The engine would still heat up as normal - if anything, it would heat up just a little faster, assuming all else 100% operational.

I still suspect thermostat.