1993 240 A/C blows hot
 

Just bought this super 240 wagon for $700! Put about $100 worth of brakes, belts and bulbs on it, and it drives great. The last thing I'm tackling is trying to get the A/C working.

It's a factory R134a system. Hooked up my manifold set and there was VERY low pressure (like 5 psi). I hooked up the vacuum pump and evacuated for about 2 hours. Let it sit for about 4 hours and the system was tight!

So I figured I'd just fill it up to test it out. It takes exactly two 12-oz cans (1.5lb) according to the label under the hood.

Started adding and low-side pressures (there is no high side port on this car that I can find) went very high, like 80 psi. I could hear the low pressure switch kick and the idle went down, then higher. It sounded like the system was working. I figured the pressures would decrease as the system started working.

I revved the car a bit and let it run for about 10 minutes, but the blower just blew hot air.

Then I noticed that the condenser fan never turned on, and the pressures remained high.

The interior A/C switch light doesn't come on (but that is one bulb I didn't actually replace, so I'll put a new bulb in it and report).

Fuses are all good.

Any ideas?


Thanks!

Ok, at first I thought you where a noob....

Are 240's equpped with r134??? not r12? Hmmm sure it wasn't converted? the high side test port has to be somewhere.

If it holds vacuum you don't have a large leak. I'm not sure familiar with recharging from those cans as I've only used professional machines. But lets say you installed via the instructions. You also need to add some oil.

What are high and low pressures with the car off a/c off? and what are they runnning with a/c on?

Is the a/c clutch engaging?

Been a while since I posted something...

It's possible it was converted, but I've read that Volvo began using r134a in 1993, a year before the mandate in the U.S. There seems to be very little info on the 1993 240 which has some interesting changes from the 1992.

Yes, no large leaks. I installed using the instructions and have done this many times before to Volvos and other cars (that's why I own a vacuum pump and manifold).

This car is different than others I've worked on because it doesn't have a high pressure port, so I can't read the high pressure. If I could, then I could better diagnose the problem.

I thought the a/c clutch was engaging, but maybe I was mistaken. It was late and I was getting tired. I'll check that again.

Is there a high pressure switch? Anyone have a good diagram?

Thanks.

i've got a 92 740 that was converted with the factory kit, there's a port near the receiver/dryer, and another down near the compressor.

I don't have the wiring diagrams in front of me, but IIRC, the compressor control comes out of the dashboard control module, goes through the low pressure switch on the dryer, and the high pressure switch on the condensor manifold then directly to the compressor, so if either switch is open, the compressor doesn't run. the signal IS the power to the compressor clutch, so +12V == on, 0V == off.

Ahh. Thank you.

So I heard the low pressure switch click, which probably means that the control module in the dash (upstream) was working. Next I need to check the high pressure switch. I found a good diagram on Volvo Parts - North Point Genuine Volvo Parts and Accessories | VOLVO OEM PARTS

As I mentioned to guest01, I'll also double check to see if the clutch is engaging... I've read several methods to correct this by manipulating the shims.

a volt meter or 12VDC test light should show the control voltages... one side of the switch on/near the dryer is connected to the dashboard AC control switch, its hot if the AC is switched on. otherside would be hot if that switch is closed (normal). that other side goes to the other switch down at the condensor manifold, again, and the others ide of THAT switch goes to the compressor. pretty simple stuff.

Yeah, I think the high side port may be at the compressor. None the less you need to find it and get us pressure readings.

getting ahead of yourself. pressure readings and visually looking to see if the clutch is actually engaging or not and if not if there's 12v to the compressor and a good ground.

That'll determine direction.

Not getting ahead of myself. I'm right on target.

High pressure switch is bad. I can jump it and condenser fan turns on, and compressor clutch engages... system works.

Now... I've read (on this forum) that there is a schrader valve beneath both the high and low pressure switches. Can anyone confirm, before I break the law and blow my refrigerant?

Also confirmed after reviewing several other forums and by searching the car last night that there is NOT a high pressure port. I suspect that the factory may have used the high pressure switch location to fill the system, particularly if there is a schrader valve under the switch.

What can I damage by leaving the jumper on the high pressure wire?

if your pressure gauge on the lowside port read 80PSI, its quite likely the pressure IS too high. which is why the high pressure switch is open.

Okay you got lucky on jumping the high side switch. far from a diag. strategy to just start jumping switches.

no idea about the valves.

leave it jumped and let us know what happens.

FYI, my 1993 240 was factory r134a