No Heat Except on HIGH.

[Sweet Lew]

Happy Holidays Everyone!

I experienced something this weekend that I thought was maybe a blown heater core on my 2007 XC70, but now I'm not sure. After searching it could be a few things; Heater core, sensor, air in system, so I'm looking for some help.

Driving around town on Saturday I noticed a maple syrup smell coming through the vents (smell is now gone). On Sunday while driving on the highway I noticed that I had to turn the heat up from 68 to 72 to get comfortable. Today I left for lunch today and had no heat except when it was on highest heat setting and then it blew hot.

The car is covered under CPO, but I want to know for my own knowledge what this could be.

Thanks,

Lew

[howardc64]

This car has a well known problem where the CCM can't get the right temperature. Here is a write up on that

http://howardsvolvos.webs.com/electricalelectronics.htm#190264577

Maple syrup smell is a leaky coolant.

You might have 2 problems instead of one. Hope this helps.

[Sweet Lew]

Thanks Howard! The car is under CPO warranty, so I'll leave it to them to remove and clean the fan.

[JRL]

No one "cleans the fan"
You just replace it, they go bad anyway

[Sweet Lew]

No one "cleans the fan"
You just replace it, they go bad anyway

Even Better!! :D

[howardc64]

No one "cleans the fan"
You just replace it, they go bad anyway

A bit more info on what happens to these fans as I've taken a couple of them apart. The fan may become noisier over time because where the fan's shaft sits seems to have become enlarged through the operation over the years. This isn't visually detectable nor can one tell by spinning the fan with their fingers (probably not enough speed or continuity). I put a dab of lithium grease in there and it all quieted down. The fan's plastic housing has plastic snaps that breaks easily. Mine broke and I had to zip tie it back together :)

Anyhow, the fan is like $150 so I decided to clean out the jammed fan spindles. Did this on both of my P2s, both had threads wrapped around the spindle preventing it from spinning. Did the grease trick on one to make it quieter.

Of course this doesn't matter for OP as the car is CPO :)

[Flathood]

Had the same problem on my newly aquired '01 XC70. It turned out the cabin air filter was packed with debris. Looked like it had never been changed. New filter solved the problem.

Charlie

[JRL]

Not with that syrupy smell
He has a leaking heater core or at minimum a coolant leak somewhere...