No heat, but cold AC. Engine temp cool

[adambombsaway]

Hi I'm new here and have tried many help sites and mechanics with no luck just lost $. So my 99 explorer limited engine temp always has run cool temp gauge never reaches half way. Also it has no heat but the AC works great. Changed the thermostat twice.. No luck the actuated door (?) in the glove box operates fine. Has started to have a high pitched "squeal" from engine when heat is on when moving from stop to go. I'm at a loss. Any ideas? I don't mind it now being summer and the AC works great. But come winter with 2 little ones the heat is DEFINATELY a necessity. I'm not losing antifreeze or overheating, actually engine temp never reaches half way as I've stated.

 

[my98nnj]

Check the heater core control valve, it's in line with the heater hoses on the passenger side. It may be stuck closed or the vacuum hose is disconnected, broken. You can manually move the valve to open it, then verify you have heat which will indicate good flow through the heater core.

 

[JimMadsen]

You can also try a heater core flush. Do it now while it is warm out. I always ended up doing it in December.

Find the 2 hoses that go through the fire wall. Disconnect both and tuck them out of the way. Using a length of clear vinyl hose that will fit the port, put the other end in a bucket. Figure 4 feet of hose at least. Use another hose and hold a garden hose to it. Slowly start increasing the water flow to keep an eye on the pressure going through. Flush until the fluid going into the bucket is clear. Switch to the other port and repeat. Switch a few times if you want.

Put it all back together, you should not have lost much "fluid" so the coolant level should be fine, burp as felt needed.

Start er up and see if you can get heat.

Simple to do, takes a few minutes. While you have the hoses off, you can inspect that valve talked about above.

 

[Ozz1967]

You can also check the thermostat, it could be stuck open.