I am new to this sight. I have been a Ford man all of my life and recently purchased a 1997 Ford F150 pickup. This body style has been a dream of mine for some time and now I have had the good fortune to be able to finally own one.

I have driven this truck for a little over a month now and the first concern that I have right now is that the heater goes back and forth between hot and cold. The temperature gauge remains constant and is within the lines of normal running temperature.

In trucks I have owned in the past...heat has never been a problem and my big concern about this one is that once the really frigid temps get here to Nebraska, will the heater be able to keep up?

Is this a normal function of the heaters in this style or do I have a problem that needs to be addressed? I find this to be annoying and my first thoughts are that maybe the themostat is not working properly (this truck has 86,000 miles on it).

The engine is a 4.2 L V6. It otherwise drives and runs nice. Any help that anyone could offer would be greatly appreciated.

 

I had a vacuum leak one time and whenever I accelerated, I lost vacuum and the vents shut down and the fans turned off. As soon as I took my foot off the accelerator and the vacuum came up in the block, it was enough to compensate for the vacuum leak and my fans would come back on. The fix was to find the leak in the vacuum hose located on the passenger’s side of the engine compartment between the battery and the firewall. I have read other post of this effecting the heat.
You can check out these posts:
http://198.65.157.241/forums/showthr...ghlight=vacume
http://198.65.157.241/forums/showthr...ghlight=heater
This one is particularly good for information
http://198.65.157.241/forums/showthr...ghlight=heater

BTW welcome to the site!!

 

I have not had this problem with my F-150 but did in a previous vehicle. If the heater continues to blow air alternating between hot and cold, it is possible that the heater core is stopping up.

 

I think you will find valuable information on your problem in the v6 forum. You say you have a 97' v6? Well, there are alot of problems with the 97 4.2 v6 engine I hear. One of the problems is a timing chain gasket leak, and the other problem is a lower intake gasket leak. I don't know if your problem has anything to do with these gasket failures or not, but come over to the v6 forum and ask your question. I'm sure there will be someone to help you out.

 

I would say keep and eye on the coolant level because your engine was built with a few obsolete gaskets; the same gaskets that are now failing on many of these trucks.

This particular problem sounds to me like your thermostat is stuck open or the heater core is clogged though. If you had a leaking gasket or were low on coolant, the engine would simply over heat. The heater wouldn't alternate between hot and cold, as it seems to.

Considering that you recently purchased the truck, I'd recommend that you first have the cooling system flushed and see if that fixes this.