No heater fan operation after A/C regas

Post by **precopster** » 18 Dec 2010, 16:43

Hoping someone has had a similar experience. I Just had my Volvo 960 regassed yesterday by my local mobile mechanic. The compressor and radiator cooling fan both work. Strangely the compressor doesn't cycle at all, just stays on. The ECC now has no fan power (fuse is OK) and it doesn't work on any speed, even if the a/c is switched off. This also means I now have no heater!! I was with him throughout the procedure. He only touched the low and high pressure valves. The cabin fan came on for about ten minutes directly after the regas and has worked intermittently ever since (about 2% of the time)

This happened directly after the regas. As you can see the accumulator is very cold and is iced up on a mild 72 degree day. The mechanic is blaming the ECC computer though the problem only began directly afer the regas. Does anybody know of any pressure switches which can immobilise the ECC fan in the cabin after a regas? We're having a killer summer here in Melbourne and after being mildly heatstroked last week I am very keen to have it working again.

Post by **billofdurham** » 20 Dec 2010, 12:19

Now that is definitely cooooooold AC.

With the compressor not cycling I would think that the high pressure switch isn't working as advertised. The AC builds up pressure on the high side and the pressure switch is supposed to cut the compressor off to maintain the pressure in the system and then start the compressor up again to build it up after it drops. If the switch is bad it will just keep pumping.

Bill.

Post by **precopster** » 20 Dec 2010, 16:10

Thanks Bill. I have an adjustable one from my old 760 V6 which was never used. I've tried to fit it but I require a new seal. Will this do the job?

Post by **billofdurham** » 21 Dec 2010, 11:13

It should do it although the systems were slightly different. The O ring part number is the same for both systems.

Bill.

Post by **precopster** » 21 Dec 2010, 18:36

Bill, Does this switch cut power b/w certain upper & lower ranges of pressure or is it just over pressure protection?

I'm asking because with almost no gas in the system the compressor was still working.

Post by **billofdurham** » 22 Dec 2010, 11:47

The pressure switch is on the high pressure line. It will shut down the compressor if the pressure goes too high or too low. It follows that if the switch is faulty it won't detect the pressure correctly and won't switch off the compressor.

Bill.

Post by **precopster** » 23 Dec 2010, 03:26

Thanks Bill, Tried an 850 pressure switch (which has a different thread, incidentally) but it allowed the compressor to shut down because I had lost quite a bit of gas when swapping it out, so it turned the compressor off due to lack of pressure.

Also discovered that my fan motor must have seized when the first blast of cold air hit it after the regassing. It had been running quite slow in the past but as soon as I hit the freeway and around 60mph with the fresh air setting the air rushing past the fan blades forced the seized fan motor to turn. Yippee!! Now I know the ECC's OK.

So now I have some dye leaking out of one of the hoses, so I'll start again with a new pressure switch, cabin fan motor, receiver-drier & orifice tube from FCP Groton. Thanks again for your help.

Post by **billofdurham** » 23 Dec 2010, 11:50

Keep us updated, please.

Bill.

Post by **precopster** » 09 Mar 2012, 17:02

Wow didn't realise I had left this thread open for so long!! It turned out that the fan motor from FCP (US market) was the wrong part and spins the other way, creating a sucking effect.

Reversing the terminal to the fan motor so positive goes to negative and vice versa actually creates airflow in the CORRECT direction and the fan seems to operate fine and at all 5 speeds.

After having the system tested under vacuum and a new condensor hose fitted they found a hole in the evaporator.
So now there's a new evaporator apparently on its way from FCP. According to Vadis it's the same part number whether LHD or RHD but VIDA says otherwise and updates the number for RHD cars. Just as well I checked. My a/c specialist is going to use the old pipes from the pierced RHD evaporator and weld them into the new LHD one from FCP.

Will update soon.