kwahaes

I have 1996 V6 Mustang that is having a heater issue. It will alternate between hot air and cold air about every minute or so. It will blow hot air while going down the road, then suddenly switch to cold air for a minute, then back to hot. It does it about every minute or so. Any ideas?

petrock

Is the A/C turning on when this happens? Does the A/C clutch engage when this happens? If so then it sounds like a short somewhere in the A/C circuit (including the control panel on the dash). Good luck...

belairbrian

Are you saying you have heat while moving and it goes cold when you come to a stop?

If so, it is likely a vacuum leak letting the temp control door change positions.

Frantz

Could also be air stuck in the coolant. Do you notice jumps in temp gauge or anything like that?

BabyGT

While that would cause something like that, air in the coolant prolly wouldn't cycle it that fast

kwahaes

I don't notice the air coming on during the time it goes cold.

I will also start paying closer attention to the temperature gauge as I haven't noticed anything but haven't really been looking at it closely either.

It alternates between cold and hot while driving or at a stop. It switched between one or the other about every 1-2 minutes. I haven't physically timed it yet, but it is starting to bug me enough now that it is getting cold and I can't seem to figure it out that I can time it if that helps.

BabyGT

Is it getting "cold" or is it just not hot anymore and blowing the same temp as it is outside.

Daehawk

Check your coolant fluid lvl.

kwahaes

I checked the coolant level and kind of topped it off. Didn't have to add much. I believe the air is just not hot, but being that it is cold outside, it is a big difference when it goes from hot to cold and back to hot again.

Dr.Le

dont know if its the same for a 96, but the same thing happened to my 99 v6.

I changed the thermostat to a 180 degree and I had the same symptom as yours.

Here's what i did to fix it. I rented a pressure test gauge (screwed on to the radiator cap and started pumping, then I saw and can hear a leak.)

It turned out i needed a $1.99 thermostat gasket.

so i bought the gasket, installed it, pressure test it again and everything was perfect. I took the stang for a drive on the freeway and the heater was hot as lava.

Hope this helps!