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        General >> Problems >> AirConPressure
        
(Message started by: iainc on Dec 3^rd, 2012, 12:29pm)

Title: AirConPressure
Post by iainc on Dec 3^rd, 2012, 12:29pm

Re Scorpy 2.3 Ult Oct 1997: Air Con
Please can anyone suggest a line of (inexpensive) investigation for this problem?

I last had the AirCon tested in 2009. I noticed recently that the demisting was just a tad tardy, taking maybe 20 secs to clear the screen than 10 secs, but it was working and there was cooling. Decided to have it re-gassed last week, for the winter. As expected, it was a bit light on gas, so it was evacuated, vacuumed (15 mins) and re-gassed with 1Kg + Oil. So far, so good, except that there is now no cooling or demisting (I noticed the fans on high speed when the engine was cold/warm). The garage has since checked it and reported high pressure in the system - they assume a blockage somewhere - which presumably triggers the high pressure valve and so prevents the gas circulating, and also to cause the fans to run at high speed. I have a good relationship with my garage, and the car is booked back on Wednesday this week. I have suggested that they put it into deep vacuum for longer (the site suggests at least 30 mins). Is there anything else that members can suggest? Somewhere on the site I read a reference to a 'big green relay' that could be jammed. If the deep vacuum doesn't cure the blockage, is there any other procedure (like back-washing a coolant system) that might work? I don't want to replace the condensor or the dehydrator (too many $$$ for a car that I will probably replace next year). Any advice much appreciated!

Title: Re: AirConPressure
Post by Simmo on Dec 3^rd, 2012, 1:20pm

The first thing to do is a Climate control reset (http://www.fordscorpio.co.uk/ccreset.htm) and see if that helps. The large green relay you mention is for the fans and is set behind the f/o/s headlamp unit on the inner wing. :)

Title: Re: AirConPressure
Post by Tompion on Dec 3^rd, 2012, 1:51pm

I assume the compressor turns & cycles on & off. You can tell when it’s clutch kicks in by watching the centre of the compressor pulley. Are the fans staying on high when the compressor isn’t running (note when it cycles off the fans won’t turn off for some seconds so it’s possible the fans won’t stop before the compressor starts again).

The compressor won’t run below a certain ambient temperature.

When I had a similar problem with high-speed fans after a recharge I reduced the level of gas a bit & the problem went.

Check the drains:
http://www.fordscorpio.co.uk/acdrain.htm

I find there’s often misting initially at this time of year if the car’s only been standing for an hour or so, even though the drains are clear moisture will still be in the heater box. If you know you’re going out again turning the AC off a mile or 2 before journey end helps prevent this as the moisture and ice gets a chance to clear.

Title: Re: AirConPressure
Post by iainc on Dec 4^th, 2012, 6:41pm

Many thanks for the suggestions.

After posting, I had the idea, like you, Simmo, of doing a CC reset. So I did that yesterday afternoon. Lots of clicking and whirring and 00 showing as per procedure.

On reflection, I think that the Big Green Relay is a Red Herring - the fans are working as per their design.

I'm pretty sure that the Compressor/Clutch do cycle (the garage would have flagged this anyway if there was a problem - the mechanic has worked with AC for years), and the fans did come back off high speed when the AC is switched off. I also had Tompion's idea about asking the garage to refill with a bit less gas. And the drains are indeed clear.

I had the car out today; I didn't run the AC on the outward journey (fear of high pressure busting the seals!), but I ran it later on the way home. I didn't hear the fans while driving, and they certainly weren't high speeding when I stopped (before switching off ignition). Which may be good news. The ambient temperature is 1.5 deg, so I don't think I'd learn much by putting a probe thermometer in the vents, and there wasn't any misting on the screen to test whether the AC was, in fact, working correctly. Typical.

I may therefore postpone the return to my garage until I've tried demisting and doing some running checks in daylight on the driveway (rather than have another evacuation and re-gassing) in case things have cleared themselves.

I'll report back on the outcome.

Thanks again.

Title: Re: AirConPressure
Post by Snoopy on Dec 5^th, 2012, 8:09am

on 12/04/12 at 18:41:33, iainc wrote:

The ambient temperature is 1.5 deg, so I don't think I'd learn much by putting a probe thermometer in the vents, and there wasn't any misting on the screen to test whether the AC was, in fact, working correctly.

The A/C will NOT work below +4C and is well documented on the main site.

Title: Re: AirConPressure
Post by Daven on Dec 5^th, 2012, 6:30pm

I had high pressure in mine a few years ago - turned out to be the expansion valve!

Cheers

Dave

Title: Re: AirConPressure
Post by lesterlad aka Rodders on Dec 5^th, 2012, 7:58pm

on 12/05/12 at 08:09:25, Snoopy wrote:

The A/C will NOT work below +4C and is well documented on the main site.

Is that just for climate control systems ?
My manual system works at temp's below 0c

Title: Re: AirConPressure
Post by Snoopy on Dec 6^th, 2012, 8:09am

Might appear to be working but the refrigerant will not evaporate below +4c even though the compressor will appear to be working.see this page in the handbook

http://www.fordscorpio.co.uk/images/handbook052.gif

Title: Re: AirConPressure
Post by iainc on Dec 6^th, 2012, 2:42pm

Snoopy

I had totally forgotten about the 4 deg thing in the handbook. That explains yesterday's non-functioning! - but not the earlier symptoms: I did a thermal probe (following the advice on the site) when the ambient temp was about 8 or 9 celsius, and there was no cooling, and the high pressure measured by the garage (which is where the car is today) isn't right.

Dave

I've looked at the replacement proc for an expansion valve: is it as straightforward as it looks (from the point of view of garage-labour-hours)?

I've passed both bits of info on to the garage. Thank you.

IainC

Title: Re: AirConPressure
Post by scorpio_man on Dec 7^th, 2012, 12:15pm

hi there

i had a sticking valve on my old car once. iirc it's just a needle valve. we cleared mine by leaving the vac pump on for at least 1/2 hour.

try that first.

hth