2000 V70R - Only Mild Heat in The Cabin

[Bluevanacd2005]

Now that it has turned cold, I started questioning why I felt cold in my car. Even with the climate control forced to heat, only Luke warm heat comes out. I have had this car several years, and this is the first I've had of this issue. Coolant level is full, and the engine temp warms right up and stays in the center of the temp gauge. No engine temperature problems here, only cabin. I felt the heater core tubes at the fire wall, and they were too hot to hold on to. The odd thing is, the heat does improve slightly upon acceleration. It returns to being cooler once at cruising speeds.

Today I removed both driver and passenger tempering air servos. They both seem to work fine, no noticeable broken parts or stripped gears. Using a screw driver, I moved the tempering air flaps myself. They moved free, but I still only seemed to get luke warm air at best.

At this point, I am suspecting a mostly plugged heater core on the coolant side. Does this sound believable?

Thanks for the help,

Spenser

[abscate]

How are the coolant return tubes - are they hot too??

I bet your heater core air side is plugged, Pull out the core - not too bad a job and I bet its plugged with spiders, mice, swedish fish, and apples cores.

[oragex]

One other possibility would be air trapped in the heater core. I had this trouble, and have a hard time purging the air. Don't know why the system doesn't purge it. I did a flush a year ago and everything was perfectly clear, no deposits, so the core is not plugged.

Accelerating causes the fluid in the core to bounce towards the fins so might explain the heat increase.

One trick to purge this trapped air is to park on an incline (the more inclined the better) with the front upwards, release the coolant reservoir cap, heat at max both sides, engine hot, then rev the engine.

[abscate]

Unlike most cars the heat setting does not influence the coolant flow on these cars - they full flow at all times

[oragex]

thx abscate, so basically it's all about the flaps being open/close?

[Bluevanacd2005]

Thanks for the help! It sounds like I'm on the right track at least!

I think I will put the servos back in but leave the covers off to access them and the core. Then I will try to bleed the core and make sure it isn't plugged. As a last resort, I'll pull it and make sure it's clean on the air side. There seems to be sufficient air flow whether it goes through the core or not, that's why I'm doing that last (and because I would be introducing air into the coolant side at that point).

I'll let you guys know what happens, but it will probably be Thursday before I get back to it.

Spenser

[cn90]

The heater core self bleeds as coolant flows through it all the time.

Chances are your tstat is bad. Get a new Wahler tstat every 70K or so.

[BEJinFbk]

+1 on a fresh T-Stat - Easy swap.

I doubt your ducts are full of anything.
It's a 2000 R - It comes with a cabin air filter.
It's probably not a factor here, but just on GP,
when was it last changed?

[scot850]

Is the cold air flap stuck open? The servo may be working, but the plastic rod/lever that operates the flap does break with age.

Neil.

[rspi]

Is the upper vent cool air vent open or closed?