Winter is coming and my heat is leaving (Bad HCV?)

[DarienFalks]

Hello all,

Winter is coming and the early mornings here in PA are getting colder with each day. Let me start off by saying the cars heater works great, gets nice and hot like it should, and all heater controls work correctly. My problem is I'll be cruising along and then all the sudden the heaters fan speed will increase (already on max) and force a lot of cold air out of the vents for a few seconds and then the fans slow back down and then the heat comes back. The car will do this most of my 12 miles trip to work. Hot cold hot cold. What could this be?

[Emons34]

Sounds like an issue with hvac control unit. The cold to hot air indicates the blend door going out of whack.

[Tre0Tre34]

no blend door that I know of. only the heater control valves for driver and passenger sides.

unfortunately I dont have much other insight...

fan speed INCREASES from the high position, accompanied by cold air? where is the air being directed in these situation? floor, front vents, all of them blow cold?

would start to think resistor pack because of the fan speed, but only the valves and control unit would change the temp

[DarienFalks]

Yeah the fan speed will increase and force more air that is could out of the vents I have air directed to. Really strange. I may just replace the HCV anyways since its probably never been replaced. Cars sitting at 83k miles right now. Once the salt hits the road I park it for the winter anyways, but I would like heat until then haha.