2004 XC70 heating issue

[das1997]

Thanks guys for all this info.

I have read a lot on here about my issue and thought I would gather everything that is happening and get some good start points.

Just this year my heater will only get hot when the car is revved up whether just stepping on gas while idling or driving. Sitting idle as I let it warm up ever day in upstate ny it will only get Luke warm. The temp gauge will rise about 3/8 and stay. The heater is Luke warm barely cleaning the windshield. If I rev it up or start driving the needle moves to 12 o clock like normal and heat pours in. I have also found that if I am driving and coast say like downhill(foot not on gas just coasting) air gets cool and as soon as I apply gas back up hill it gets hot again just holding hand over vent.

When idling I went out last night after reading here and checked both lines to the heater going in the cab. Top one is hot and bottom is Luke warm. Assuming both are hot when driving as I did not have anyone to rev it up for me while holding it and has hot air moving.

I have checked the reservoir and it is between min and max.

Never overheats and has been great car since I bought it in 2012.

Thought I would start with the thermostat but didn't seem like my first move after reading here.

Any advise on where to start?

I did have to replace my blower last year but all has been well since then.

Thanks for any help
David

[chrism]

If the engine never overheats, then I would not suspect the water pump to be the cause.

It sounds to me like the thermostat is suspect - maybe "almost" closing but not quite restrictive enough when idling.

[oragex]

First thing, roule out air trapped inside the cabin heater, or cabin heater faulty. When you turn left at speed, does the cabin heat increase? Might mean an air bubble is trapped inside.

To check for a thermostat stuck open (most usually the way it fails) start with a cold engine and let it idle for 2 minutes. Touch the upper radiator hose that goes from the thermostat. If it started to warm up (that is before the thermostat should have started to open), it means the thermostat won't fully close any long and that will cause all the issues you describe with the cabin heat when accelerating.

The XC 2004 is turbo I guess. If so, I think this is the thermostat for it, it comes only with the whole casing (double check to be sure)

http://www.ebay.com/itm/Beck-Arnley-143 ... f4&vxp=mtr

It's pretty a hassle to replace. The serpentine belt comes off, the power steering pump must be put on the side (don't disconnect anything), drain the coolant, remove the radiator hose from the thermostat housing (flat screw driver from an angle to remove the collar), then - my suggestion to make it easier - split open the thermostat housing pictured and replace only the upper part with the sensor and the thermostat and the seal. The thermostat must have the burping pin upwards.

[das1997]

Good morning, I looked at your part and do i have to buy the whole housing or can we just replace the thermostat inside? I have a gmc so this is why im asking and the repair doc shows just the stat and not the housing. I have a 2004 xc70 awd turbo. Thanks, David