Looking at '04 XC70 - no heat - high beams

Faust · Post by **Faust** » 20 Dec 2021, 16:18

Found myself looking at an '04 XC70 today. 160K, extremely clean, sticker for an expensive beach, and apparently dealer serviced. Timing belt changed at 135K. I was disturbed by no heat. Blower works fine, couldn't test blending doors. Bringing it up to temp, I felt the heater hoses. One was at best "warm" other seemed ambient. No obvious sign of a heater core leak. My non expert opinion suggests a clogged heater core. Any suggestions of what, or how, I should test for other problems? Since any blockage seems severe, what method to flush?

High beams - this must be a simple one. I hope. High beams work when the stalk is held in the "passing" or "high beam" position. releasing the stalk causes the high beams to shut off. I am looking for suggestions because the relay in my '05 is built into the computer and is a very expensive repair.

Faust · Post by **Faust** » 20 Dec 2021, 21:11

Here is what I am thinking. Anyone tried this?

Post by **erikv11** » 21 Dec 2021, 00:16

You have to gamble on whether or not it's the heater core for purchase sake, but seems reasonable it is.

I think I'd pull the core and see if its blocked, yes. But then probably put in a new one rather than mess with flushing it out. Depending on age I suppose.

One question is why did it get blocked? Are other parts of the system clogged up? Hard to address that but something to consider.

Post by **abscate** » 21 Dec 2021, 04:29

Heater cores are full flow. If it’s blocked it’s either a really neglected cooling system or someone used glue in it, aka StopLeak, instrument of the Devil, Faust.

You push the stalk forward on a P2 to get high beams, I think? Check manual for operation.

Faust · Post by **Faust** » 21 Dec 2021, 06:56

abscate wrote: ↑21 Dec 2021, 04:29 Heater cores are full flow. If it’s blocked it’s either a really neglected cooling system or someone used glue in it, aka StopLeak, instrument of the Devil, Faust.

You push the stalk forward on a P2 to get high beams, I think? Check manual for operation.

I understand the fear of Stop Leak. As I look around the web, blockage in the core seems a very common problem with Volvos. Culprit seems to be small passages and corrosion. Seems like a very large number of DIY videos on replacing the core in P2 cars. On seeing the price of a new core, circling around $100 as opposed to $584 from Volvo, replacing the core is probably the better job; also, a rather simple one.

High beams - Electrically speaking, I am on a level with Ben Franklin. The stalk switch, according to my '05 manual, has the normal 3 positions, low beams, passing, high beams. The blue light on the dash comes on and the high beams operate while the stalk is held. This indicates the the bulbs and wiring are correct, leaving the stalk switch, or an intermittent relay. I suspect I had best fool around with the three position dash light switch, which I have never really understood.

Post by **abscate** » 21 Dec 2021, 07:04

Just look in the coolant reservoir for gooey crap (ISO 14001 approved term) to see if someone pooched it. There are far fewer P2 heater core threads than P80 even after adjusting for age in my meta-analysis

Faust · Post by **Faust** » 21 Dec 2021, 07:14

abscate wrote: ↑21 Dec 2021, 07:04 Just look in the coolant reservoir for gooey crap (ISO 14001 approved term) to see if someone pooched it. There are far fewer P2 heater core threads than P80 even after adjusting for age in my meta-analysis

"Gooey crap", good call. I had thought of looking for an "icky" appearance.

Post by **regent** » 21 Dec 2021, 09:24

Dr. Faust,

If you want to change the heater hoses on that baby, I have the 30745333 and 30745332 sitting in my garage, pls PM me

motormikeyman · Post by **motormikeyman** » 21 Dec 2021, 09:49

The high beams will only stay on if you manually turn the headlamp switch on. Otherwise they will only come on if you hold the stalk back. It's in the owners manual somewhere.

Post by **850 LPT** » 21 Dec 2021, 09:51

First thing I would do is throw a new thermostat in there