Hi all! I've searched numerous times, but I must ask.

I have a 240, that when I got it, the A/C didn't work.. The previous owner just said it stopped working when I asked.

I checked for voltage at all the relays and put some r134 in it (PO had converted) The compressor decided to kick on! However, it seems that the compressor will cycle on and off. It will go on for, 5 seconds or so, and be off for, maybe about 10 seconds, but those are just rough guesses. I have the cheap r134 gauge and the system seems to be holding pressure, and I can see the pressure fluctuate when the compressor kicks on and off. I have put maybe about 3/4 a can of refrigerant in the system but it doesn't seem to take anymore. Assuming the system has enough pressure(I'm not sure it does, but for the sake of troubleshooting I will assume it does) What else can I look at? From other posts it seems it may just be the clutch on the compressor? IF that's the case, where do I get a new clutch, or is this a model that can just be reshimmed?

Thanks for all the help
-Gregg

 

Greg, what year is your 240? The later models have both a high as well as low pressure switch. A failed high pressure switch could be making it cycle off too soon. However, without a decent manifold gauge set it's impossible to diagnose. If the system was empty when yo started due to a small leak, the system was at ambiet pressure. It will not take much refrigerant atall. The systemhas to be pumped down to a vavuum of 25-30 inches and hold at least 25 for 15-30 minutes to check for leaks. If there are no leaks, the R134a has to be introduced while vacuum is present. Harbor Freight has manifold gauges for $30 or so...great for home mechanics. I would bet there's just no vac in the system...the high and low pressure switches can fail, but it sounds like they're workin. You just don't have enough refrigerant in the system and you won't without pulling a vacuum frst.

 

Sorry, didn't mean to leave out the year...it's a 1991. I appreciate the insight and I know I am at a disadvantage without the gauges - there is a harbor freight somewhat close to me - I should pick up a set.

Assuming I do pick up the set - what would be my next step? I have a vacuum pump I can use.

 

Well, there is a difference between recovery and pulling a vacuum. Polar bear will drown if you vent the existing 134 to atmosphere. Having cleansed my conscious, pull the vac for 30 minutes or so. Manifold gauges have backwards *****. They are off turned all the way counterclockwise for installaton and removal. You turn them in all the way to open the valves. Readings vary depending on ambient temp, idle speed, efficiency of the condensor and several other factors. Basically, you want to add refrigerant until the high side reads 200ish and the low side reads 30-50. If you aren't confident, take it to a shop. If you go to Harbor Freight, get a thermometer probe and stick it in one of the central vents. Shoot for 38 degrees...anything lower is icing on the cake. Add the refrigerant SLOWLY!

 

Thanks for the procedure - I'm pretty confident I can do this, the A/C would be a luxury and looking to spend as little as I can if possible.

Going back to my main post, is there something I can check that will tell me Yes it's the clutch or YES it's definitely low on refrigerant?

 

On 80's models the compressor cycles on and off as a way to regulate the temperature, this is normal. The rotary switch inside is what supplies power to the clutch, depending on the pressure (temperature) sensed from the expansion valve.

 

What is the cycling period? How long on and how long off? Does it apply to a 91?

 

The 91-93's used a GM style system which I have no experience with. The cycle time on my 86 varies alot with the temperature and the switch setting .. but normally its on for ~15-20 and off for ~10 on a hot day, during idle.

As stated already the next step would be to watch your low side pressures .. they should always be in the 20-32 psi range while running. Alything less than this would suggest low refrigerant, tripping the low pressure switch.

 

Gotcha - I will have to pick up the manifold gauges for better troubleshooting, but on the cheap walmart gauge for refilling the low pressure port the pressure does not drop below 25 while the compressor is on.

 

This pretty much explains it all:
http://www.brickboard.com/FAQ/700-90...rClutchCycling

And applies to your 91 GM system. It is normal for the clutch to cycle.

 

Thanks for the reading - so I suppose since I put in the r134a i actually don't have a problem anymore and haven't let the thing run long enough to get cool? Just assumed the cycling means there was a problem.

 

My 1989 wagon (first new car my wife and I purchased new) never had really cold A/C. I have noticed the 1990's Volvo's have an electric pusher fan that runs while the A/C is on. Has anyone retro fit an electric fan to their 240? Did it help? Are you still running R-12 or did you convert to
134a? Has anyone got an 134a system that puts out 37 degree air? I replaced my fan clutch years ago, it did not help.

 

I had taken the Volvo on a trip to New Orleans last week - the car ran SOLID for a 500 dollar car. Of course the A/C did not work - The compressor was running, but none of the lines get cold - I have the idea of keeping this as a daily driver / commuter car / extra car so I would like to get the A/C going. I don't mind putting some money into it - I am thinking first with a a seal kit and then replacing the drier unit since I'm sure it's old and could possibly be bad.

Can anyone lend some advice on this or try to point me in the right direction?

It's a 1991 240 sedan automatic transmission. The previous owner converted the low side fitting to R134, and I threw a can of that in it and the compressor came on. It runs but the lines themselves don't get cold.

Thanks for the help!

 

My 1989 took 2-1/2 cans of r-12 "replacement before the sight glass on the dryer was almost clear. I attached a 134-a fitting on the suction side to use a cheep a/c charge kit. Runnig down the road the outlet air will range from high 20 degree to low 40's as the compressor cycles . I have a hand held digital temp gauge. You can not run the a/c in town the car will get hot. Years ago I changed the fan clutch - it did not help. I still think a pusher fan is the way to go. Your 1991 may have
a GM stile a/c system. I do not know what the difference is, compared to my 1989 system. Do you have a dryer with a sight glass? Don

 

My 87 240 wagon A/C was always unsatisfactory from day one. I and my wife don't even bother using it during city driving on hot days...................it'd just waste of gas.

 

My system does not get cold. I had a digital thermometer in the vent and at nite it was pushing a cool 70 degrees at idle. My drier does not have a window.