1994 V6 Intermittent Air Con - Mustang Evolution

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Old 08-12-2018, 06:50 AM   #1
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1994 V6 Intermittent Air Con

Hi all,

In the 20 months or so I have owned the car the AC has never worked. Earlier this year I took it to a place to get it checked and they confirmed that the Compressor is not working and needs replacing. I decided not to proceed at that time.

For the first time in ages we had a day where I needed to clear the windscreen today so I put the dial round to Window but forgot to set the temperature to hot. After a few seconds cold air was coming through. And it was proper icy air, not just ambient cold. It stayed this way for the journey I was doing - around 4 or 5 minutes.

Got back in to drive elsewhere, no cold air. It was just ambient temperature and not cold at all. Another 5 minute or so journey.

I then came back home again - a 10 minute journey - and started playing with the dial. Norm AC, Max AC, vent, windscreen, nothing, just ambient. After a few more moves of the dial, cold air started coming through again on Norm AC. And it was cold!

So, where can I start looking for this one - there's obviously a loose / damaged connection somewhere - maybe behind the dials themselves?

Interestingly, I have a Jaguar X-Type as well which had a similar issue and that was found to be a relay in the fuse box - could I be that lucky again?

Thanks in advance for any pointers.

TMW
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Old 08-12-2018, 11:10 AM   #2
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Hi all,

Quick update.

I went out again this afternoon but had left the dial in the "NORM AC" position. Air was still cold. I did not touch it.

Also, I forgot to mention, the dial for setting the temperature sometimes feels a bit resistant - I am wondering if there is something inside the mechanism that could be blocking from turning and registering properly? Sometimes it works fine, others it doesn't. Basically, if I don't go to the extreme ends it seems Ok, but if I do, that's when I get strange things happening...

TMW
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Old 08-13-2018, 02:00 AM   #3
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It could be a problem with the mechanism that operates the air blend door inside of the HVAC box.
If you look up underneath the dashboard on the passenger side, you will see the cable and mechanism for the blend door. You can remove it and see if it is operating correctly. You might also be able to check the movement of the blend door after the mechanism has been removed.
If there is a problem with the blend door itself, unfortunately, it requires removal of the dashboard and the HVAC box to access the blend door.
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Old 08-13-2018, 12:39 PM   #4
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It could be a problem with the mechanism that operates the air blend door inside of the HVAC box.
If you look up underneath the dashboard on the passenger side, you will see the cable and mechanism for the blend door. You can remove it and see if it is operating correctly. You might also be able to check the movement of the blend door after the mechanism has been removed.
If there is a problem with the blend door itself, unfortunately, it requires removal of the dashboard and the HVAC box to access the blend door.
Thanks for the response - will take a look.

You don't think it could be related to the dodgy dials as well - something not making contact and therefore not triggering the signal to start something up?

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Old 08-13-2018, 03:00 PM   #5
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Yes. It could be a problem with the HVAC control panel as well. You mentioned the temperature control dial being sticky. That is the dial that controls the blend door. If that door is allowing the air to pass over the heater core, the air will never get cold even with the air conditioning compressor turned on.
The HVAC control panel is easy to remove from the dashboard. You will just have to do some digging around to diagnose the problem.
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Old 08-14-2018, 12:44 AM   #6
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Yes. It could be a problem with the HVAC control panel as well. You mentioned the temperature control dial being sticky. That is the dial that controls the blend door. If that door is allowing the air to pass over the heater core, the air will never get cold even with the air conditioning compressor turned on.
That's correct - there's "resistance" for it to get to the full hot and full cold positions and it pushes back slightly - if you don't go all the way it seems to work fine.

I will see if I can get another control panel from somewhere in the first instance - but will also have a look under the dashboard as per the original response later today hopefully too.

Thanks again.

TMW
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Old 08-14-2018, 12:00 PM   #7
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That's the switches / controls on the dash causing the problem. Pull it out & check for a loose connection. If none are lose .... go to a junkyard & pick one up for $5 - $10 & replace it. Also...replace your fuse.
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Old 08-14-2018, 12:03 PM   #8
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If you are getting air flow no matter which position your switches are in then the door has nothing to do with it.
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Old 08-14-2018, 12:06 PM   #9
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That's the switches / controls on the dash causing the problem. Pull it out & check for a loose connection. If none are lose .... go to a junkyard & pick one up for $5 - $10 & replace it. Also...replace your fuse.
Cheers. I have found one on ebay that could be a winner.

Which fuse should I change?

Thanks in advance.

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Old 08-14-2018, 02:03 PM   #10
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If you are getting air flow no matter which position your switches are in then the door has nothing to do with it.
The air temperature blend door does not stop nor redirect the flow of air inside the vehicle cabin. It merely allows the air passing through the HVAC box to come into contact with the hot heater core.
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Old 08-14-2018, 11:11 PM   #11
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The Fuse that goes to your A/C in the fuse box. It could be weak.
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Old 08-15-2018, 10:07 AM   #12
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The Fuse that goes to your A/C in the fuse box. It could be weak.
Will check the handbook and see which one it is.

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Old 08-18-2018, 07:03 AM   #13
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Hi,

Well, I have just been out playing with dials and settings etc. for 20 minutes or so and I cannot get it to fail at all. All dials and settings are working exactly as I would expect with regards to speed, direction and temperature, including AC running vs AC not running.

I don't get it.

It's like it has magically fixed itself after all this time...

I do remember I once had my Jaguar checked when that had a faulty compressor (that one really was) and they said if I run it if there is something not quite right it can sometimes just ping back in to life - looks like that's what has happened here...

Strange - but good!

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Old 08-27-2018, 12:25 PM   #14
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Hi all,

It failed again!

Could not get a thing through yesterday.

Checked the fuse - all good.

Did some snooping and reading and looks like it is the AC Compressor Clutch sticking and not always engaging. I have seen it spinning correctly and also not doing anything so I know that's the culprit.

Have seen a Youtube video on how to change it - looks relatively straightforward. But the question is, do I change just the clutch part or will I need a whole new compressor as well?

Thanks in advance.

Regards

TMW
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Old 08-28-2018, 09:53 AM   #15
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I think that I would try changing just the clutch first. It can be done without having to recharge the system with refrigerant.
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Old 08-28-2018, 02:13 PM   #16
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I think that I would try changing just the clutch first. It can be done without having to recharge the system with refrigerant.
That's what I was thinking - thanks for confirming.

Regards

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Old 09-01-2018, 12:55 PM   #17
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Working fine again today!



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