S70 ECC Problem--Weak Cooling and No Passenger Side AC . . .

[EricGagnon]

Hello:

I've started to chase a problem that I'd like to ask for some help with from others here on this forum, which has been a great information resource for me with our recently purchased 2000 S70 GLT SE.

The AC with on our dual temperature control ECC was blowing weakly cold, so I attached a manifold gauge set to the low pressure port and put in some additional refrigerant, which did help a little, but AC performance was still not great. Pressure on low pressure port is 50 PSI at idle and 40 PSI at 2000 RPM. I don't know how to connect to high side pressure so don't have those readings.

One thing I discovered today was that temperature readings from an AC thermometer on the two driver's side vents (center left and far left) are different than those for the two passenger side vents (center right and far right).

With BOTH driver and passenger side temperature controls set to maximum cooling (6 o'clock) and AUTO with max fan speed, the driver's side vent temperature for both vents was 68 degrees (just OK, but I think should be cooler, like at least 50 degrees). However, the vent temperature for both passenger side vents were just blowing ambient air temperature at 80 degrees.

The AC buttons on the ECC unit are also flashing, so I know there's a code being thrown in there as well (I'd also appreciate any suggestions for a good OBD-II reader that can also read Volvo ECC codes).

Mechanically, everything else seems to be working O.K. with the AC system--compressor cycles on normally, fans come on, etc.

Has anyone experienced a problem like this one? I know my next move is to pull the code from the ECC and see where that takes me, but I'd certainly appreciate any suggestions for other things to look for or try.

I'd really like to fix this on a DIY basis if I can since I know these ECC repairs can get expensive in a shop. This car is in great mechanical shape otherwise with only 51K miles so it's definitely worth the effort.

Thanks,
Eric

[sleddriver]

Wow...you have a 2000 S70 with only 51k miles? It's a time machine. The 98 sled has > 220k mi. Wow....amazing difference that.

Electrically our cars are quite different. Obviously the pass. side blend door motor or door isn't working or is stuck or a plastic gear has lost some teeth.

Run the engine to 1500 RPM, then note the dash air temp for all vents. Next mist the condensor with water from a pump up sprayer and re-measure.

[EricGagnon]

sleddriver:

Yes, 51K miles and a fair amount of service work done on it by the previous owner (timing belt, water pump, brakes, steering rack, etc.) so it should be a nice car when I get the remaining bugs worked out of it.

Thanks for your info on the blend motors. I took your tip and did some additional research here and on YouTube so I get the picture of what needs to be done.

Other than cooling down the condenser, what's the reason for spraying water on it?

[abscate]

I wrote a reply here which got lost in the ether...

The Volvo climate system sets temp by cooling all air (AC ON) and then blending the cold air with warm air from the heater core. The two sides have different blends, so you can set two different temps.

When you have blend door fault, your AC can be fine, it is just getting killed by the heated air!

68F from a full on AC is not good though - if thats at 90F ambient, thats only 22F temp delta. A good Volvo AC will do 2x that, and 35F delta is still respectable.

An AUTEL 5xx series or up will read the ECC control unit codes and give you a hint as to what is wrong

[Chuck W]

I made a DIY tester, as described HERE

Worked great and helped sort out the issues with the wife's '97 GLT.

Able to read codes, clear codes, as well as do the damper motor actuator position reset with this.

[EricGagnon]

abscate--thanks for the info on blend doors and temperature. This is what I'm thinking too.

Chuck W--I saw your video earlier with your DIY tester--very interesting.

I'll get to work on finding the codes and will post what I found.