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Heater barely works. Why? Topic is solved

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msyverts
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Heater barely works. Why?

Post by msyverts » Tue Dec 18, 2018 8:46 pm

(I moved this here since I put it in a "solved" topic the first time.)

Got the car in 2014, a 2001 V70 2.4T. Loved the heating and cooling system the first few years, I just set it at 72 year round and it was always comfortable. Only problem was that I started getting a puddle under my feet in winter, from a leaky heater core. i had an independent shop replace it (not a Volvo specialist) and that stopped the leaking. I don't know the source of the core but it was not genuine Volvo (though I've heard a lot of people do fine with ones from ebay). Somewhere about that time, though, the heat stopped working well. After reading other posts, I noted that reconnecting the battery can cause problems, and I hadn't known of the procedure for turning the key to II before reconnecting (!). So now I'm not sure if the problem traces from the core replacement or any of the many times I've had the battery off for one reason or another.

In favor of the core being OK: The inlet tube was at 172 deg. F (back, farther from firewall), and the outlet at 160F (closer to firewall). The far (passenger, right) side of the core was 162F. The thermostat housing at that point was 192F. The temps probably not perfect since all i had handy is a quick-read kitchen thermometer, but at least it has a small probe and is responsive.

In favor of the CCM being OK: when i turn temp knobs all the way to hot, the air still isn't very hot. Warm, but not crazy hot like my wife's VW. But now that I think about it...maybe this means the blend doors aren't all the way moved to the heat position? If so, is that CCM fault or mechanical in the doors?
The door levers all moved when I turned the knobs and pushed the vent buttons, but I don't know how to tell if the doors have moved to full heat position, especially while the core is still in place.

In favor of the CCM not working right: it used to turn up the fan a few minutes after starting the car from cold, as the engine had warmed up. It doesn't seem to do that. Also, even though the temp in the car is well below whatever the knobs are set to, it doesn't try very hard to make it warmer.

So, next step?
Replace core again? (Just noticed one tube is leaking ! so need to at least change the o-ring)
Flush out the core? (Doesn't seem like it lacks flow from temps)
Calibrate CCM?
Try to read CCM codes?
Check the thermistor in the CCM?
Somehow determine if the doors are getting to the right place? Preferably without pulling the core?


Thanks for any help!



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SuperHerman
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Re: Heater barely works. Why?

Post by SuperHerman » Tue Dec 18, 2018 10:24 pm

Thermostat?



msyverts
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Re: Heater barely works. Why?

Post by msyverts » Sun Dec 23, 2018 8:10 am

I have been assuming not the thermostat since the temperature gauge acts like it should: goes up to the middle in 10-15 minutes and stays there. Also temperature at the thermostat outlet was 190F. Thanks though.



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Re: Heater barely works. Why?

Post by cn90 » Sun Dec 23, 2018 10:11 am

Look for my DIY on 2005 XC90 2.5T thermostat DIY using only tstat w/o the need to remove the PS Pump.
Very easy DIY if you follow that DIY.
Use only Wahler.

The temp gauge is buffered so you don't see the fluctuations.
The thermostat is usually gone by 90K-100K.


2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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Re: Heater barely works. Why?

Post by Georgeandkira » Tue Dec 25, 2018 9:18 am

The core line's leak sounds like an urgent first priority, no? Eyeball the doors then if you go that route.

Read any CCM codes next as this is the easiest step. Address any issues found. Might a faulty "thermistor" trigger a CCM code? Is this the temperature reading device (grille) in the dashboard? I haven't vacuumed mine. I should.

Recalibration of the CCM, if done by some combination of dial setting/button pushing/battery disconnection-reconnection, sounds like a next step.

A worn thermostat comes up so often I'd consider it next.
Being a thermostat is such a basic, predictable maintenance item I might just change it first.
Your kitchen thermometer may have been reading the temp of hot metal.

UNIMPORTANT NOTE: Tomorrow is the 2nd anniversary of owning my V70.



msyverts
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Re: Heater barely works. Why?

Post by msyverts » Tue Dec 25, 2018 9:16 pm

@Georgeandkira, happy anniversary and thanks for the thoughts.
@cn90, thanks also.

I'm starting to favor the thermostat theory because I took a long drive with the family today, and evenually it got too warm and I was able to dial the setting back to 72. When I turned it on full, the air actually got really HOT like it's supposed to! Pretty much all of my driving is 30-45 minutes. So maybe it's really not coming up to temperature. Plus I've never replaced that thermostat.

Yes, the core line leak should be urgent but I put up with a puddle for way too long when the core was leaking before, so the carpet has already been through that. I guess I don't want to just replace the o-ring (which seems to be the leak) if I will later go back and do the whole core for some reason. Plus I'm more patient about the leak than the actual heat.

So I think I'll do the thermostat next chance I get and see how that goes.



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Re: Heater barely works. Why?

Post by msyverts » Wed Dec 26, 2018 8:44 pm

OK, I learned some more things today but the heater is no better.

I took out the thermomstat and it works perfectly. Doesn't budge until it nears 195F, then opens up wide. It's Volvo and Wahlers branded made in Germany. For now at least I put that one back in.

Then I took the hoses to the heater core off at the engine side of the firewall, and put the garden hose on one of them. There was no problem at all running water through the core. I vacuumed the tap water out and flushed in new coolant mix.

I looked at the levers for the flaps and I'm pretty sure that they do move all the way to the heat position. I can't see the doors themselves, but the levers move into the same position as in the video by cn90 that shows them move, with one pointing horizontally to the back of the car and the other one on that same shaft at about 5 o'clock or 4:30. So, assuming these are the right position for full heat, the CCM is doing its job correctly.

At this point I figured the core must just be bad, perhaps has an internal hole that lets the coolant bypass most of the core and go back out. But...

I put everything back together and refilled with new coolant mix, and warmed it up at idle so I could fill the last bit. I got 6 quarts out when I drained it, and it took that much back in.

With the engine fully up to temperature, though, I felt the hoses at the firewall. At first both were cool! After a bit longer the left side one warmed up, but the right side one stayed stone cold. Inside the car, the front side of the heater core was cool, and the back side was slightly warm.

So, what's going on?

It seems like something is keeping the flow from going in to the core. It's almost like there is a second thermostat built into one of the heater hoses, but it takes an hour to open.

Any ideas?

My next thought would be to try starting the engine briefly with the hoses taken off of the firewall, to see if I can confirm there is a flow problem there. Except it would drain itself really fast if it is flowing and that's probably not great. Maybe I could connect the hoses with a clear section of tubing so I could see what's going on...then need to take more things apart until there is flow...or maybe take the hoses off and apply pressure at the coolant reservoir and see if coolant will come out from the hoses...is there a good diagram of the piping somewhere?

Thanks all.



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Re: Heater barely works. Why?

Post by SuperHerman » Wed Dec 26, 2018 10:42 pm

Good work. Sounds like your heater core is blocked. It is basically a mini radiator. Hopefully some one will chime in if the core has some sort of valve (I am assuming it does not in what I would do).

It is possible you have an air bubble or a physical block. Most likely a physical block.

Have you thought about trying a back flush? Basically run water (or air) through the core in the opposite direction. Place a collector hose and bucket to catch what comes out and a hose on the intake side - then run the garden hose. Take it easy with pressure - use some common sense. Remember it is a mini radiator - so it can develop a clog.

Have a look here: https://www.wikihow.com/Flush-a-Heater-Core

There are some cleaning solutions for radiators, I have never used them, but some have had good luck.

I suppose if it was me, I would drain all the coolant, assuming it is new and fresh to reuse. Then try back flushing, as described above. If you find crud and it opens up, I would buy some coolant system flush, follow directions and then once you are happy finish the system as required.

After all of this you may find your heater core is past its life span and spring some leaks. No way to know, but the least intrusive and cheapest route is trying a flush.



msyverts
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Re: Heater barely works. Why?  Topic is solved

Post by msyverts » Sun Jan 13, 2019 9:23 pm

I replaced the core today. I put some additions to others' notes in the post at https://www.matthewsvolvosite.com/forum ... =9&t=84522

I think the core was the problem. it flowed great but had poor heat transfer. Once I finally got it out, I compared it to the Behr core that I had bought. The Behr core has twice as many cross tubes, and they are smaller diameter. The previous core has 11 tubes on each side, all in a line. The Behr has about 22 staggered ones on each side, for a total of 44.

So I think the advice to get the Behr core is good.

The other one I believe came from ebay, but had no manufacturer's markings. It might be OK for a mild climate but really didn't cut it in Wisconsin.

I'm hoping it will work like it used to when i drive to work tomorrow. I'll post a follow up.



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Re: Heater barely works. Why?

Post by msyverts » Mon Jan 14, 2019 9:26 pm

Yes! Heat is back and strong like I remember it used to be!

It took a long time to decide to change the core since it wasn’t obviously bad, but clearly it didn’t have the same heat transfer properties as the OEM one. Here are photos for comparison.

Note the different size and number of tubes, visible through the ports.


64624624-08C4-42D6-B123-1EFFD5E204CB.jpeg
The no-name core (Black) and the Behr core (off white)
467BC572-541D-4591-9470-DC849CDDDF83.jpeg



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