I've been tasked with fixing my father-in-law's air conditioner in his S70. My shop manual on CD is en route, but the car is already here so I've got a few questions. First of all where is the high side service port? I've looked in all the places that it seems like it should be and I've yet to find it. Next step will be to climb under it and start taking off the plastic covers. Which is really okay since I believe there is a leak in the system anyway.

On the low side service port I read about 50 psi static pressure. When the compressor kicks in that pressure drops to just under 20 psi before the pressure switch disengages the clutch and stops the compressor. Adding refrigerant helped for about 90 seconds and the situation returned to exactly what I've just described.

My belief now is that there is a leak in the high circuit between the compressor and the expansion valve. I just gave it a shot of dye and I'll climb around the car with a black light later on when it cools off some.

So am I on the right track? Is there anything that I'm overlooking at this point. I'm relatively new to AC work, but am trying to understand and get better at it. I really appreciate any input on this matter. Thanks.

FWIW this is an automatic transmission, non-turbo car.

 

It seems that there is no high side service port. It also seems that I'll be tearing into the dash going after the evaporator core. It'll be an adventure for sure.

 

I guess you figured out about the high pressure port.
The evaperator will take you some time but it is not really all that bad.
Refer to the instructions I made into a post on how to replace the evaperator.
Did you find dye leaking from the drain?

 

I'll be sure to look for dye in the drain. I'd talked to my father-in-law after that post and a dealership had told him that the evaporator was what went. I haven't confirmed it for myself yet, but I feel pretty certain that they're right. Thanks for the heads up on your instructions, funny how things like that seem to hide in plain sight sometimes. I've printed a copy and will dig into it after work tomorrow. I'm usually pretty terrible about documenting these types of projects but I'll try to take pictures of the steps you outlined and get them to you for a pictoral write up.

Not being a Volvo owner myself, I've little long term use for this site, but I am grateful that it and you are here. The Internet never ceases to amaze me in terms of just how much valuable information is available to those willing to seek it out.

 

Keep us posted on your progress.

 

Using your instructions, which were reasonably close to the reality of this 1999 S70, I got as far as removing the dash tonight. Parts (evaporator, drier, expansion valve) should be here on Monday). Over the weekend I'll get the evaporator and drier out and do some cleaning. I did take quite a few pictures. I'll go through them later.

 

Cool looks good!!!

 

So I got the AC working, it blows really cold.

I had to have the SRS light reset. Unfortunately though it was immediately re-triggered. It is an SRS DTC 12. The scan tool that pulled the code called that an unspecified error. Any ideas? I felt certain that I had triggered it by starting the car with the passenger SIPS plug disconnected, but its coming back and I don't know why yet. I plan to pull the steering wheel and glove box in the morning to double check all the connections, but I think I was pretty thorough when I put everything back together. Hopefully it'll turn out to be something dumb, we'll see I guess.

 

It should be something simple.Just double check all connections.
Im glad it went pretty good for you.

 

I triple checked all the connections to no avail. The light won't stay off. Without a more specific description of the fault, I don't even know where to start now.

 

Did it stay of before until you test drove it?

 

The light comes back immediately after being reset. As soon as the key goes back to the on position, the SRS light remains on.

 

Yes but I meant when it first came on.
Sometimes the SRS contact reel breaks if the set screw is not installed when the steering wheel is pulled off.

 

When it first came on was after I had reassembled the dashboard. I had the passenger seat SIPS disconnected because I had unmounted that seat and pushed it back to give myself more room to work. I wanted to test the dash and make sure the car would start before I went further with the job. That is why I was so certain that it would stay off after being reset, I knew that I had inadvertently done something to trigger it.

As for the contact reel, I did use the set screw, but FWIW the upper mounting tab was seperated from the rest of the reel when I opened it up. Since the light was not on before the work I did, I didn't place any significance on that fact. The reel's electrical connections and placement behind the steering wheel did not seem to be adversely affected by the missing mounting tab as there are two others that seem to adequately secure it's position.

I wish I had access to a factory service manual. They often have better descriptions for DTCs and will sometimes provide step by step troubleshooting instructions (measure the resistance between these two pins on connector such and such for example). I don't feel like my chances for success in running this down are very good without such a resource.

 

One thing we did while we were in school was use a paper clip to jump the connector to fool the computer.
Volvo makes special tools that are nothing but resistors to be plugged into the wiring to fool the computer into thinking thr air bag is hooked up.

Your scanner doesn't tell you which air bag it is?

 

It's not my scanner, it belongs to a local independant Volvo repair shop. It's an Assenmacher Retriever (http://store.autotoolexpress.com/ass5700.html). It's pulling SRS DTC 12, but the description simply says "unspecified fault". If it was my tool then I'd probably spend some time isolating different parts of the system and seeing if a reset sticks after a certain section was isolated. But I don't feel comfortable Easter egging on the shop's time. The owner was already nice enough to give me two for one on the SRS reset attempt, I don't want to push my luck.

I've returned the car to my Father-in-law. If he can get a better diagnosis, I'll offer some more work, but otherwise I think it's just gonna have to be a dealer fix.

 

Ok keep me posted on the progress.