1996 850R Fast cycling a/c compressor / idiot check

[dmack87]

OK so my wife's 96 850r wagon is blowing warm air. Buy a can of 134A with the gauge on it and hook it up to the low port near the passenger front of the engine compartment. As I understand it, the reading on this gauge is only good when the compressor is running correct?

So I start the car up, put it on max a/c and the compressor is cycling on and off continuously. I fire some 134a in there, and the compressor seems to settle down a bit. I am watching the gauge reading only when the compressor is engaged, but it only seems to stay engaged for 5-7 seconds then shuts off for like a minute or more. So I'm standing there squeezing the trigger only when it is engaged, and after about 15 minutes, the reading when engaged appears in the center of the area where it should be. Problem is, the compressor won't engage at all now. It just sits there and does nothing. I take it for a quick drive, and no difference in the a/c.. still blowing hot.

Now I get nervous an think "crap.. maybe I am reading this backwards as the gauge is clear at the top of the redline when plugged in so I allow some 134a to accidentally escape to hopefully head off disaster, and it goes right back to doing the fast cycling thing on the compressor. At this point I feel like a complete idiot and I assume I just wasted a bunch of my 134a, however nothing I am doing is having any impact on the a/c temp at all. It just seems to be screwing up the compressor.

So here is what the gauge reads when the car is off, but if I understand it, this reading is meaningless right?

and here is a video of what the car is doing now when running:



When the gauge needle is rising is when the compressor is on, and when the compressor is clicking is when the compressor is off right?

So now I don't know if I undercharged it, over charged it, it's just plain broken, or I am just a moron who should not be allowed to work on cars. Anybody want to straighten me out here?

<dispirited_rant> I just ordered $1200 worth of parts for this car on FCP and now feel like I should just sell the dang thing since all I ever accomplish is finding more stuff wrong with it, or perhaps breaking additional things </ dispirited_rant>

[scot850]

Hi dmack, welcome to my world! Could be worse, you could have an AWD! I bought what appeared to be a well maintained car with history about 2.5 years ago. Only 6000km (4000 miles) and I am already $13000 into it with another $3000 about to be ordered!

What can go wrong on my car has gone wrong and in a big way!

850R's are a simpler car and would be they way I would go with hind-sight.

Once it is running ok, it will be worth it, honestly!

As to your question, I am not an A/C expert by a long way, but a few pieces I have picked up with these cars on this forum are as follows:

1) Compressor clutch not maintaining engaged. Check MVS for paper-clip repair. Seriously, it could be that simple!
2) Are the A/C lines getting cold? Could be the system is working, but if you have ECC (Electronic Climate Control) the flaps can jam, and will not allow cold air + A/C air to circulate.
3) With ECC there are (IIRC) 2 cabin temp controllers. Over the years these get clogged up with air-born crap and stop working. These are above the 2 front seat grab handles above your head at the door. You need to remove the grab handle and the trim piece along the top of the door to allow you to remove them. Mostly they just need careful cleaning, a little light lube and re-fitting.
4) The Evaporators fail. This is a PITA job to fix requiring removing the whole dashboard. There is an excellent write-up in the repair section (ask how I know!!). This is where I would take the car to a good A/C specialist and get them to pressurise the system with gas and a dye to see if there are any leaks in the system before spending any more money on it. On our 93 850 it was the evaporator, on my 2000 R it was a goosed compressor with bad bearings.

I'd do #2) first as it is a free fix to see if the temp controllers are working, and then get the dye/pressure test done before spending any more money, other than for the paper-clip. Again there is a write-up for that.

Neil.

[Ozark Lee]

The gauge reading is only valid when the compressor is running.

When the compressor is running the pressure will drop on your gauge. The gauge reads the suction side of the system.

In a static state (compressor off) the pressure will typically get well in excess of 100 PSI on a hot day.

There is no reason to panic, just keep charging it until the compressor stays on and you get your gauge reading in the green and more or less lined up with the ambient temperature on the scale below the green field. It won't be exactly correct but it will be close enough.

It reminds me of a billboard that is around town right now that has "Your Wife Is Hot!" in big print and below that in a smaller font is says "Better get your air conditioner fixed".

...Lee

[dmack87]

Neil - I will be looking in to your suggestions. I hope it is not the evaporator! For the paper clip thing, are you talking about the bread clip thing with the compressor, or using a paper clip to bypass the compressor relay?

Lee - I got another can of r134a today. The only thing that is weird is that the compressor seemed to stop coming on at all after I had incorrectly thought I was over charging it. Is there enough value in having an actual gauge set vs the single screw on type that comes with the can or refrigerant? I am new to a/c, but willing to buy a set of gauges if needed.

[Ozark Lee]

As far as getting a manifold gauge set, they have limited utility on a Volvo since there is no high pressure service port on the system. The gauge you have pictured will show you everything that you would see on a more expensive manifold gauge set. Where a manifold gauge set is handy is when you buy R-134A by the 30 lb jug like I do and they are also very handy for other makes of cars that have both a high pressure and a low pressure port.

If you bled the system thinking it was overcharged you may not have enough left to trigger the low pressure switch (pressostat). You can stick a jumper wire into the connector for the pressostat and probably get the system to come on but you need to be adding R-134A as you do it. The compressor can get damaged if you you trick it into running and let it continue to run without R-134A to circulate the oil.

The pressostat is the sensor that is on the larger A/C line near where it goes into the firewall.

...Lee

[scot850]

Clutch fix with bread clip which was what I was thinking of, sorry for my error!

Here is a link to a how to...

https://www.matthewsvolvosite.com/forums ... c&start=20

Hope this helps.

Neil.

[erikv11]

I use zip ties instead of bread clips, I think it is a better way to go.

https://www.matthewsvolvosite.com/forums ... 0&p=251228

[misha]

My advice is to take the car to ac specialist service to check the system.
Maybe the ac compressor is low on oil and,if it is,if you keep topping it with r134a....you will fry it because it have nothing inside it's oil sump to lubricate it.
One part of oil is circulating through the system along with r134a and one part of oil stays in compressor's "oil sump".
This is something which is not advised to be done in DIY version unless you have all the tools required for servicing the ac system and knowledge about the system.

[busyangel1]

I had this problem with my 97' 850. A local shop looked at it and saw it was fully charged. Unfortunately he decided to add freon anyway and caused a pinhole leak in the hardest place to get to on the car. When I returned he told me about this (and said no charge for the freon he used)(but not about it losing pressure now) He then did what he should have first when the gauges read normal during the short cycling, he looked it up on the computer. A few minutes later he came back out removed a sensor and wiped it clean and Viola ! it worked perfectly (for 8 wks) then it did need freon and a very difficult repair. Be aware of overcharging if your gauge reads normal range while compressing. Another bit of useful info is to use an ambient temp / pressure chart when charging the low side of the system.
eg. at 65 degrees you should read 30-35 psi .....add 5 psi for every 5 degrees hotter up to 80 after that then 85-90 degrees is 45-55 psi 95 to 110 degrees outside is 50-55 psi. There is usually a little indicator you can set on your gauge to mark normal range for whatever the outside/ambient temperature is. Your service manual should have the specs for your cooling system. The example I quoted is the standard R134a temp/press. chart. I now do mostly all of my own repairs on my 850 and she purrs and rides like a Sunday only car. I have 115k and figure I'm good for the same again. My wife likes driving the 850 better than her late model 6 cyl. Camry LE and so do I. Hope this info saves someone some trouble and helps get you cooled off once again.

[abscate]

The charge is for an equilibrated system...fan on high, max cool, and engine rpm 1500 or higher so that compressor runs at full capacity. Record the temperature differential between ambient and the AC outlet at the dash..on an excellent system, after 15 minutes, you can see 40 F temp delta. 30 is still pretty good, 35 better. I think a lot of people get the charge wrong doing this at idle speed based on the procedure for the variable displacement compressors found on other cars.

If your AC tech is charging your system at idle speed, they probably don't know what they are doing and will overcharge.

Jimm57 did an excellent write up on this I'll find and link to. I believe I put into the VRD.