overheating when idling

Go Metric · Post by **Go Metric** » 29 Aug 2016, 15:15

*update* overheating with AC off and on during idle. Just much faster with AC on.

My 2002 v70xc is having some weird ac issues. I did the ziptie/breadbag trick last year.
Low pressure side has way too high pressure. When idling the clutch won't ingage on the compressor, and the engine overheats. I have zero overheating issues when not using AC. The AC also works fine when I'm cruising along.

Anyone experience this before? Pressure switch? Expansion chamber?

It's not the cooling fan, I replaced that and that comes in when the compressor is running . It does NOT come on when the ac is on but the compressor isn't running.

I first noticed on a hot summer day earlier this month. I was in a big parking lot when I started the car and turned the ac on. It worked for a moment, then the compressor disengaged and it would only blow warm air while I slowly crept around the parking lot. But when I got on the highway it worked fine, fof several hours actually, as I was on a road trip.

But then I hit a traffic jam, and the temp shot up. This has happened consistently several times, so now I just stopped using the AC except occasionally I'm driving on the highway.

Post by **chrism** » 30 Aug 2016, 10:24

When you say the low pressure side reads too much pressure, is the compressor running at the time that pressure is measured, or is the compressor idle? The compressor needs to be running, otherwise the low side will read high and the high side will read low - actually, they'll read about the same if the compressor is idle.

Also, have you tried taking a garden hose and blowing out the air passages in the radiator and condenser, from the backside-forward? The radiator may be all bug-clogged.

Go Metric · Post by **Go Metric** » 31 Aug 2016, 16:51

It reads way too high while the clutch is engaged and the compressor is running. It will run for the first 20-30 seconds when you turn it on during idle, then disengages and eventually causes overheating.

My radiator blew last month, and was replaced. Then we noticed the fan wasn't coming on, so I replaced the fan with a pulled Volvo fan of the same model & part number. I haven't tried to clean out the condenser though, because I hadn't thought that could cause the clutch to not engage on idle.

I will shamefully admit that when I released some of the pressure (I know, very bad thing to do), it ran at idle fine for a couple days but now it's doing the same thing.

Go Metric · Post by **Go Metric** » 31 Aug 2016, 17:15

Ok so it just happened again for the first time WITHOUT the AC on.

I replaced the fan myself, and I had to drain some coolant to do it since I had to remove hoses. I may not have bled the system properly. Any tips on bleeding out any leftover air bubbles that could be potentially causing this?

Post by **oragex** » 31 Aug 2016, 18:29

This car burps itself. Is the radiator fan speeding up when the temp gauge goes past 12 o'clock ?

Post by **vtl** » 31 Aug 2016, 18:56

Unless 02V70XC is radically different from 02V70 and 05XC70, you don't need to touch any coolant hose to take the fan out.

Do you have a decent code reader, which can read some common sensors? What is you actual coolant temperature when overheating happens? Failing thermostat or coolant temperature sensor is a common issue at the age of your car. I had it already replaced in both my wagons.

Post by **chrism** » 31 Aug 2016, 22:04

Let's talk about the new radiator - any chance it's not flowing enough volume?

When the old radiator blew, did the engine overheat?

Go Metric · Post by **Go Metric** » 01 Sep 2016, 07:00

oragex wrote:This car burps itself. Is the radiator fan speeding up when the temp gauge goes past 12 o'clock ?

I haven't been able to check because I'm always driving (stopped at a red light or something of the like) but I'll try to check and see next time it happens.

vtl wrote:Unless 02V70XC is radically different from 02V70 and 05XC70, you don't need to touch any coolant hose to take the fan out.

Do you have a decent code reader, which can read some common sensors? What is you actual coolant temperature when overheating happens? Failing thermostat or coolant temperature sensor is a common issue at the age of your car. I had it already replaced in both my wagons.

It's a turbo, so to take the fan out from the top I definitely needed to move the hoses. It was just too tight of a fit otherwise, I tried!

chrism wrote:Let's talk about the new radiator - any chance it's not flowing enough volume?

When the old radiator blew, did the engine overheat?

That's definitely possible. I bought it New from FCP, but it was not Volvo brand, it's a nissens.
When the old radiator blew, I was pulling into the parking lot at work downtown on a very hot day. I didn't notice the temp gauge shooting up, and I didn't get a high temp warning message and alarm that I remember. The radiator main overhead hose blew off with the broken end of the fitting inside it still.

Post by **chrism** » 01 Sep 2016, 08:17

Nissens is a respected brand, as far as I know.

Did you mess with the thermostat at all?

Also, If you start the engine cold and let it idle as it warms up, can you lay your hand on the upper radiator hose and sense when the thermostat opens and hot coolant flows back to the radiator? You should be able to sense, with no doubts, when it opens.

How many miles are on the water pump?

Go Metric · Post by **Go Metric** » 01 Sep 2016, 09:09

I will definitely try the hand on the hose test very soon and report back.
I have not messed with the thermostat at all, it could be an issue.
The water pump was replaced when I had my rear main seal, timing belt, etc all done last summer about 25k miles ago.