850 A/C issues

hrm · Post by **hrm** » 08 Jun 2008, 19:28

I recently purchased a 1994 850 Wagon and the A/C does not work correctly. It's been over 90 degrees here this weekend and I'd like to get it working. Here's the symptoms, codes and what I know so far.

Heat - Ok
Fan manual - Ok
Fan Auto - Seems to adjust fan speed to adjust heat/cool needed
A/C - Nothing. only hot air blows out compressor does not cycle on at all

Codes: I originally had 414 & 417 I blew out the interior temp sensors with compressed air and now I get 126 I didn't get a chance to pull the sensor and see if I can get that code to go away.

Diagnostics. I checked the A/C relay and it appears to be operating correctly. I pulled it and applied 12v & grnd and got power on the correct posts. plus when I put the relay back in I switched the A/C on and off and could hear it click.

I put 12v power directly to the clutch and it activated correctly.

I get the blinking lights on the dash but that appears to be from the 1-2-6 code as it reappears as soon as I clear it. Will that keep the compressor from activating even if I'm in manual blower mode?

What else might be keeping the compressor from activating? I haven't had a chance to check refrigerant pressure - I guess it could be too low. Can I jump the pressure switch temporarily to see if the compressor comes on correctly?

What should I try next for diagnosis? Thanks everyone in advance. I've looked through a number of posts here on this site as well as others to get me this far, but now I've reached the limit of my volvo knowledge.

hrm

Post by **Ozark Lee** » 08 Jun 2008, 21:02

You really need to get a gauge on the system before you jumper the switch. If you do indeed have pressure it might just be low on refrigerant. If it has no pressure you don't want to jumper the "pressostat" as it could destroy your compressor very quickly due to lack of oil.

No pressure means that you have a huge leak in the system. Sometimes you will get lucky and it is a leak in the accumulator but usually it means that the evaporator is toast. There is a terrific writeup in the database on how to change the evaporator but it is a huge job. I start it tomorrow onthat project with my son's car.

For all of the codes that the ECC will throw a low coolant charge isn't one of them. All of your codes point to interior temp sensor problems. The 414 and 417 are interior temp fans seized (driver's side and passenger's side) and the 126 is that it is just mad about the passenger's side sensor in general. None of those will kill the A/C compressor.

The chain auto parts stores sell recharge kits for around $30.00 that have an integrated pressure gauge. If you have a harbor Freight in the neighborhood they sell a cheapo gauge set for about the same money. Check the pressure first.

...Lee

hrm · Post by **hrm** » 09 Jun 2008, 06:08

what pressure am I looking for? and is that measured with compressor on or off? I guess at this point I can only measure with compressor off, since I can't get it running yet. So what is the off pressure I should see if it's pressurized correctly?

Thanks.

Post by **Ozark Lee** » 09 Jun 2008, 06:46

The pressures vary with ambient temperatures but 100ish PSI with the compressor off and mid 30s PSI with the compressor on is in the ballpark.

...Lee

Post by **JRL** » 09 Jun 2008, 07:20

Ozark Lee wrote:The pressures vary with ambient temperatures but 100ish PSI with the compressor off and mid 30s PSI with the compressor on is in the ballpark.

...Lee

...and if you're totally out of freon it takes exactly 1.63 lbs of R134A

hrm · Post by **hrm** » 10 Jun 2008, 14:14

Found out this morning the system has very little pressure in it. The gauge did move but not a whole lot. Should i try charging it and seeing what happens? or what? obviously the pressure has been released somehow, either through a crack or having been let out intentionally before I bought the car. I know very little of the repair history.

Suggestions? Thanks everyone.

Post by **MadeInJapan** » 10 Jun 2008, 14:25

Let me suggest you get 3 or so cans of gas with dye in it and buy the funky yellow glasses and black light kit to trace fault the leak. Go ahead and fill it up... see what happens. If it's a large enough leak it won't last but a day or at most 2 at the most. Hopefully in the dark with the A/C running you'll be able to see where the leak is. If you don't see the leak at all but know it's leaking, most likely it's your evaporator (it's in the nooks and crannies under your dash so you won't be able to see the leak there with the dye/light). An evaporator replacement is very expensive...about $1500 because the entire dash has to come out. Personally, if you can keep gas in the system for a few weeks to a month it's almost worth adding a can of gas once or twice a month but eventually the hassle becomes such that you want to bite the bullet and fix what's wrong.

chuckcintron · Post by **chuckcintron** » 10 Jun 2008, 14:27

Fill it with 26 ounces of the R134a you get from Wal-mart. Get the hose with the gauge on it, so you can see what it's doing (pressure-wise). I think those cans might be 13 ounce, so IIRC I would just throw two cans worth in there.

You'll know if you have a leak...could be a day later, a week...if a really minor/slow leak some folks get away with a month. If you hear the compressor start to short-cycle you'll know it's losing its charge.

-Chuck

hrm · Post by **hrm** » 10 Jun 2008, 20:23

yeah so I filled it this evening and the A/C blows out nice and cold (would have been better last week when it was 95+) so we'll see how long it lasts. hopefully a long time..although if it gets me through the summer I'll be pleased. I tend to be a windows/sunroof guy, but when it's over 90 it's a little too warm for the windows only.

Thanks