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        General >> Problems >> Ventilation
        
(Message started by: Penguin on Dec 27^th, 2006, 9:27pm)

Title: Ventilation
Post by Penguin on Dec 27^th, 2006, 9:27pm

Had a bit of bother with the Scorp on a long run this afternoon. After about twenty miles of the journey the cabin ventilation dropped right off, as in the amount of air comming into the cabin became insuffient to even keep the windows clear let alone allow me to breathe comfortably.

I reset the system (SATC - no faults showing) but the problem didn't go away. It turned out if I turned the fans right up I got a weak blow of air from whichever vents were selected but if it wasn't all the way up there was practically nothing. The fans themselves were clearly working from the noise they were making.

In the end I was forced to switch off the system and open windows. When I got so cold I couldn't bear that any longer I turned it back on without the air-con on and it seemed to be working better. After another twenty miles it seemed to be working fine. At that point I turned the air-con back on and it was still working fine.

I will, of course, change the pollen filters at the first opportunity, but is this likely to have been caused by anything else and is it likely to happen again?

Cheers

Penguin

Title: Re: Ventilation
Post by scorpio_man on Dec 27^th, 2006, 9:37pm

hi there

does your system cycle on and off (watch the clutch move)?

sounds like it's icing up. check these 2 pages.
http://www.fordscorpio.co.uk/acmod.htm
and http://www.fordscorpio.co.uk/deicetest.htm

please note, DO NOT MODIFY YOUR SYSTEM. we think there was a change to the thermistor on the later systems. the mod can blow your compressor/seals.

hth

Title: Re: Ventilation
Post by Penguin on Dec 27^th, 2006, 9:51pm

My system is modded already, although the mod is not switched on in these temperatures. I found the mod rather useful in summer so I'd rather not have it removed if I don't have to. Will it really be such a problem?

I'm not sure how to check if the system is cycling, where is the clutch and how would I see if it was moving?

Cheers

Penguin

Title: Re: Ventilation
Post by scorpio_man on Dec 27^th, 2006, 10:03pm

hi there

you can see the clutch at the r/h/s of the engine (low down on the front of the compressor).

up to you regarding the mod. ;) blew my system to bits! it's all down to the return temp of the gas to the compressor (all a bit techy). when it's high temp outside, start the system in rec mode for the first wee while. this will chill only the inside air, not new fresh (hot) air from outside.

hth

btw, the engine fans (both) will cycle on and off in time with the clutch.

Title: Re: Ventilation
Post by Penguin on Dec 27^th, 2006, 10:05pm

Okay, I'll have a look at it tomorrow morning. Which should it be doing - cycling or not cycling?

Cheers

Penguin

Title: Re: Ventilation
Post by scorpio_man on Dec 27^th, 2006, 10:11pm

hi there

it should cycle on and off. it will be on for a bit longer at start up just to reduce the temp at the thermistor to just above freezing.

hth

Title: Re: Ventilation
Post by Penguin on Dec 27^th, 2006, 10:15pm

Thank you!

I'll check it tomorrow and report back.

Cheers

Penguin

Title: Re: Ventilation
Post by Penguin on Dec 28^th, 2006, 10:48am

Seems to be cycling fine and the fans are operating in tandem as they should be. Also, from inside the cab, the system seems to be operational.

I did, however, forget to turn the a/c off over the last few days when it dropped below 4 degrees (I read somewhere else on the forum that this temperature seems to be the point that one should cut it out). Could the thing have frozen and then not defrosted when the car was turned off because the ambient temperature was below freezing at the time?

Cheers

Penguin

Title: Re: Ventilation
Post by Johnboy on Dec 28^th, 2006, 2:50pm

Hi scorpio_man,

Are you saying this mod http://www.fordscorpio.co.uk/acmod.htm, should not be done to the scorps. I was thinking of doing it on my 98 model.
If this is the case and it may blow the system, would it be a good idea for Admin to remove this mod from the scorpio site.

Cheers

John

Title: Re: Ventilation
Post by harry.m1byt on Dec 28^th, 2006, 2:55pm

I vote for the freezing up blocking the airfllow - you could have confirmed it by watching for the drips of water from the drain(s) in the bulkhead (under the bonnet and at the back of the engine), or drips onto the road as it defrosted.

Title: Re: Ventilation
Post by Penguin on Dec 28^th, 2006, 3:00pm

Yes I think you're right. When I parked it yesterday after the problem there was very little water dripping, but when I went back for it later in the evening there was what looked like several days' worth under the car.

Cheers

Penguin

Title: Re: Ventilation
Post by harry.m1byt on Dec 28^th, 2006, 3:30pm

on 12/27/06 at 21:51:59, Penguin wrote:

With the switch off, it should be reverting back to Ford standard and therefore should not be a problem. How robust is the workmanship of the mod? If it shorts out across the switch, it will run continuously and ice up as you describe.

Title: Re: Ventilation
Post by Penguin on Dec 28^th, 2006, 3:48pm

My mod was bought from Daven of this forum and installed by my (trustworthy) garage according to the exact website instructions, so one would assume it's okay in that respect.

I'm no electrician - but wouldn't a short out across the switch give the mod no resistance at all, and thus make it permanently off rather than permanently on?

Cheers

Penguin

Title: Re: Ventilation
Post by harry.m1byt on Dec 28^th, 2006, 4:55pm

As I understand it, the resistors are placed in parallel with the temperature sensor. The lower the resistance switched in the harder it forces the a/c to work, the off position inserting no resistance - therefore a short across the sensor would be the same as a a high temperature indicated by the sensor.

I'd be a little surprised if the CC didn't therefore assume that the sensor was out of range though, with a short across it.

Title: Re: Ventilation
Post by Penguin on Dec 28^th, 2006, 4:59pm

Well the system itself says no faults and it is cycling normally now - I think I just froze it by (accidentally) running it in sub-zero temperatures and then leaving it parked it sub-zero temperatures so it never had chance to freeze...?

Cheers

Penguin

Title: Re: Ventilation
Post by scorpio_man on Dec 28^th, 2006, 5:24pm

hi johnboy

re the mod. i should have added the word some. as in some cars might have a problem (mines did). i know of a few cars with the mod which don't have an issue. my a/c explained it all to me (the techy bit). said it was a bad idea in general to mess with the system.

i guess it's a take your chance sort of thing.

imo, not a good idea and very costly when things go wrong. :(

Title: Re: Ventilation
Post by TiberiuS on Dec 28^th, 2006, 6:22pm

I always have my AC on, the way I understood it was that it dried the air even when it was freezing cold outside, didn't think it possible for it to collect enough ice to block it.

But...

Last year (2005), does anyone remember the hottest day at the end of August?, was about 35c in London. The autobox was dying at the time, came off the A12 at Brentwood and started losing gears, pulled over to let it cool down and plumes of steam/smoke started billowing out. Let it cool and fearing the worst took a peek, all fluids were ok and the only thing I could see was a large pool of water under the AC; car was fine aftewrwards, never happened again. Mabye the matrix froze then (possible in 35c heat?) and thawed all over the manifold as I switched off the engine, I'm not sure. No mods on my AC either, the old lady is a handfull as it is...

Regards, Bruce.

Title: Re: Ventilation
Post by Daven on Dec 28^th, 2006, 7:49pm

on 12/28/06 at 14:50:15, Johnboy wrote:

Out of around 50+ mods I have supplied plus the countless number others have made up, I only know of 3 cars that had problems of some sort - each had different symptoms and the only thing 2 had in common was the thermistor part number being different to some of the other cars (results from a poll at the time!).

I checked this during the batch Penguin was included so I assume his thermistor is not one of the suspect ones (if that is the case!).

The systems are 10 years old - any work carried out comes with a risk.
The chances are the mod will get the blame even if its coincidence and for this reason I will no longer be supplying them - I don't like the feeling each time I read something like this!

Harry.m1byt the mod Penguin was supplied was tested and is unable to 'short' unless it was installed incorrectly - if this was the case he would have found out by now (unless he has only just installed it!)

Title: Re: Ventilation
Post by Penguin on Dec 29^th, 2006, 12:03am

The mod's been installed (and working) since June so I do not seriously suspect it as being a problem now.

(I'm guessing that if it had come disconnected - which is the only thing that can go wrong with a switch - then the system would be spilling out fault codes on the basis of not having a thermistor reading?)

So I think the options are as follows - either the system froze because the air-con was running in low temperatures and it was also sub zero at night so the car couldn't unfreeze then, or there's something physically wrong (rather than electrically wrong - if so there would be a fault code) with the compressor. I'll run it for a while over the weekend (now it's not very cold) and see if it does it again.

Cheers

Penguin

Title: Re: Ventilation
Post by harry.m1byt on Dec 29^th, 2006, 10:04pm

on 12/28/06 at 19:49:57, Daven wrote:

Harry.m1byt the mod Penguin was supplied was tested and is unable to 'short' unless it was installed incorrectly - if this was the case he would have found out by now (unless he has only just installed it!)

I wasn't pointing the finger of blame in any particular direction, simply indicating a range of possible faults I would be inclined to look for.

I base this upon many years of experience fault finding - you start by listing all of the possibilities, listing them in the most likely order, then eliminate them one at a time. My apologies if my earlier comments caused any offense, that was not the intention.

Title: Re: Ventilation
Post by Penguin on Dec 30^th, 2006, 6:23pm

Solved it! ;D

Yes, the system had frozen over.

Reason - the mod.

Specific reason, I had the mod set to max rather than zero by mistake. :o

So that proves two things - the first that Daven's mods are very effective, and the second thing is that the car's aircon unit is very strong because now it's thawed out it's all working fine as if there was never a problem.

Cheers

Penguin

Title: Re: Ventilation
Post by Daven on Dec 31^st, 2006, 8:56am

harry.m1byt " My apologies if my earlier comments caused any offense, that was not the intention."

None taken Harry. ;)

Penguin - the mods were not designed by me, I just made some up, it was PeteC and SteveC who put in all the hard work! ;)

Glad you have found the reason - I have been working on an freeze alert that should indicate when the system is getting too cold! I just need someone with a bit more electronics experience to check/improve the design! Any one out there?

Dave

Title: Re: Ventilation
Post by harry.m1byt on Dec 31^st, 2006, 8:52pm

on 12/31/06 at 08:56:26, Daven wrote:

Glad you have found the reason - I have been working on an freeze alert that should indicate when the system is getting too cold! I just need someone with a bit more electronics experience to check/improve the design! Any one out there?

Dave

Dave, bung the design my way. I'm a bit out of touch with the very modern stuff, but I'll happily cast an eye over it.

If I were doing it, I'd probably be looking at a ZN 423 (I think that is the right number) precision temperature sensor feeding into an op-amp comparator - output of which feeds an LED and/or a peizo sounder, all fed from a 5v regulator. Add a pot onto the other pin of the op-amp to act as a reference. There will be cheaper methods, but I think the precision will be needed for this job.

Title: Re: Ventilation
Post by Daven on Jan 2^nd, 2007, 2:06pm

Cheers Harry - can you PM me your email address and I will sort out the info!

Was looking at a simple thermistor and the LM3914!

Had a working model until I shorted it out and blew it up!! :-/

Dave

Title: Re: Ventilation
Post by harry.m1byt on Jan 2^nd, 2007, 5:38pm

PM is harry.m1bytNOSPAM@tiscali.co.uk (remove the NOSPAM).

The bargragh IC - I thought that might not provide the accuracy needed, but if you have tested and it was OK, fine. Are you actually using it as a bargraph, or just using one of the outputs to trigger an alarm? Might be better not to have to watch a bargragh whilst driving, but handy when combined with an alarm too.

I don't know how this might work, but could you not just sense when ice was actually building up and use that to trigger an alarm. A couple of probes insulated from the metal stuck on the fins, then detect the conductivity of the ice forming - perhaps a bit of PCB with the tracks forming the probes. I know the conductivity of the water will be poor due to it being pure water and ice will be even poorer.

I use a similar bit of PCB on the motorbike sensing wet, to trigger a chain lube system into doubling its output when it rains.

Why not go the whole way and automate the system -so it has feedback knowing the system is icing up and turns itself down a bit?

Title: Re: Ventilation
Post by Daven on Jan 3^rd, 2007, 8:17am

Harry - cheers will send you the info.

I had considered a fully auto device, but as I said in a previous post I worry if any thing goes wrong that may point to something I have supplied - so I went down the 'keep it simple' route.

Another point to consider is the fitting of it - the mod is bad enough as you have to remove the windscreen wipers and motor, grill etc. let alone getting to the fins.

I will continue this in an email - if anyone has any ideas or suggestions please PM me!

Dave