C8 2.2 Aircon

[MixerFistit]

Setting aside my more serious problems while I look at some little niggles.
If anyone has any info, it will be appreciated.
Aircon hasn't worked since I had it so I've done the following:

Freed the siezed intercooler fan and replaced the 30A Maxi fuse in the engine bay.
Was unable to run the larger fan neither through lexia nor direct off a 12v battery so swapped it with the one from my old Dispatch (that was a 3 wire, 3 speed type so I shorted the 2 + wires to allow max speed and spliced the plug off the other fan and also had to mod the housing slightly). So both fans now work great. High speed and low speed both kick in on Lexia and by fast idling I managed to get them to trigger at approx 100 C (forgetting I could've just unplugged the temp sensor )

So back to aircon (Climate controlled): I had some R134 left over so gave it a blast. It didn't take much before the compressor kicked in and I thought my luck was in.

Nope.. All it seems to do is make my engine warm up quicker and I get either ambient air temp or maybe even slightly warmer air through the vents.

It's been 3 days and the compressor still kicks in so there doesn't seem to be any leaks (at least not any obvious catastrophic ones).

The other thing is I cannot activate cooling fan through lexia (I can under injection as mentioned above). There's 2 options. Compressor test and fan. Only the compressor makes the click sound, the fan test does nothing. Is there a different fan hidden somewhere? Different relay for same fans?
There is a 40A maxi fuse in the engine bay that is labelled as A/C blowers in the handbook but it seems perfectly intact. But that at least suggests there's another circuit somewhere that may need investigating. Any clues to those are greatly appreciated.

Or..

I'm only adding r134 from a bottle as a quick top up, I'm not pulling any vaccums or doing it the professional way. So maybe it's just that is the problem?

I do notice the pressure is much higher with the compressor off. When aiming for the correct pressure is it when running or when not running or shouldn't it be wildly changing in the first place? - I tried aiming for the goldilocks zone for both on and off and neither gave cold air anyway.


Out of curiosity and slightly off the point, how are the front fans even wired? It seems they both rely on the other to function. I had to put my voltmeter on a pin of each plug to get any sense when I was fault finding, as I said, I've got them working now but still interested to know how it works, it seems to be able to regulate the speed somehow by using both fans and doing something clever even though both fans work normally with a 12v direct source (individually, my old dispatch fan was more complicated with it's 3 speeds but when the C8 fans are looked at as a pair, I can't work out what's happening)

[ozvtr]

I'm only adding r134 from a bottle as a quick top up, I'm not pulling any vaccums or doing it the professional way. So maybe it's just that is the problem?

I do notice the pressure is much higher with the compressor off. When aiming for the correct pressure is it when running or when not running or shouldn't it be wildly changing in the first place? - I tried aiming for the goldilocks zone for both on and off and neither gave cold air anyway.

If air has gotten into the system, adding R134a is not a good idea. Moisture will react with R134a and cause internal corrosion. If the system had a bit of pressure in it when you started, you could assume that no air had gotten in. But then you know what Benny Hill said about "assume".

Pressures are not an accurate way to determine the performance of the system. It gives a good indication, but you would need to obtain the pressure/temperature/humidity performance charts for that particular system, to be "accurate". I have not seen one of those for a long time. The pressures in the system vary dramatically with temperature, compressor speed and load. So getting and idea of how well an AC system is doing by using gauges requires interpretation. However an indication is better than nothing.

As an indication, a fully charged systems' static pressure would be about 70psi @ 20'C (ambient temp), 100psi @ 30'C. Static pressure is the pressure of the system when the system has not been used for a couple of hours and has stabilized.
As an indication, when the AC is running, with the car at idle, the low pressure side would be between 25 and 40psi. The high pressure side would be between 150 and 250psi. As I mentioned before, these results depend on the ambient temperature and the load on the system (has the car been siting out in the sun or under cover?).
Having said all of that, the best indicator is how comfortable the driver feels!!

If you are using one of those "can and a hose with a gauge" things, you will need to find out the weight of refrigerant required for a full charge of your system. Then buy enough cans to do the job. The net weight of the refrigerant is printed on the side of the can. Adding refrigerant by weight is a quick and easy way to charge an AC system. An average AC system with a TX valve takes about 500-600gms of R134a.
The best way to get the most out of any one AC system is to monitor the temperature of the air at the vents while adding refrigerant. The AC system will produce the maximum cooling at the optimum refrigerant volume. Too much or too little refrigerant will reduce the cooling capacity of the system. Even just a little too much refrigerant could cause a high side pressure cut off on a hot day!
The fact that the compressor kicked in when you added a bit of a charge to the system is encouraging. However it sounds like it wasn't enough to produce a noticeable change in temperature.
While AC systems are NOT designed to leak, it's a fact that some systems may leak. Although, the leak should be VERY small. A leak that causes you to "top up" every couple of years seems to be acceptable.

[MixerFistit]

Thanks for the reply, some useful info there.
I guess if it's holding pressure I've at least got the confidence to have it done properly with a vacuum.
I don't have much confidence in the gauge as it went up pretty quick. Maybe that's a sign of a lot of air trapped and a leak since sealed