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Old 16th January 2021, 17:05   #1
bikerdude666
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Default Rad fan and air-con not working properly

I'm in need of some advice, back on Christmas eve I had to drive through some flooded roads. I took it steady, and initially it seemed the only problem was a heat shield being knocked off the underside, and the bottom corners of the arch liners being pulled out of place. Between Christmas eve and 4th Jan I only used the car for 1 quick journey to go and help a neighbour start his Boxster, and I didn't notice anything wrong.

However, first day back to work on the 4th, I started the car to let the engine idle while I opened the gates. A I opened the gates the car just didn't sound quite right, but being 5am I didn't have time to look into it more, and put it down to not being used much for little over a week, and it being a very cold morning. But the car hasn't sounded right since, and I finally had a day off today so had a quick checkover of a few things.

I noticed the cooling fan isn't coming on, at first I thought it was broken completely but it does come on every minute or so for around 15 seconds.
I found a test on here, bridging 2 pins in a connector on one of the aircon pipes. bridging the 2 pins furthest apart, there was a slight delay and then the fan started up. The other test was to bridge the pins closest together, but nothing seemed to happened anywhere.

When pressing the auto or econ button, there used to be a noticeable change in engine noise, and a slight drop in revs when auto was pressed, I could definitely tell audibly between air con being on and off. Now it always sounds the same, regardless of what buttons I press on the heater controls.

I took off the FOS wheel arch liner so I could have a look and check the belt was still attached to the aircon pulley, it was. While I had it off I started the engine and got my son to operate the heater controls while I watch the pulleys.

When he pressed demist, the air con pulley was spinning, he then pressed Auto and the outside of the pulley was spinning, but the middle was stopped. I realised it was probably because it was set to 20 and it was 6 outside, so I got him to turn it down to 16, then tried again.
So demist pressed, no fan at the front, and both parts of air con pulley spinning.
Auto pressed, no fan at the front, and bother parts spinning.
Econ pressed and no fan at the front and outer part spinning, middle stopped.

I then left it on auto for a bit and the fan at the front started up for a few seconds, then went off, came back on a minute or so later, etc

I fitted a gold resistor about 5 or 6 years ago, but I'm guessing the flood water may have killed this? Hopefully solve that issue with a new resistor. What I need some advice on is the aircon. As far as I can tell, the pulley is doing what it should when on auto/demist/econ. So what could be the problem cause no drop in revs, no change of engine sound? And what exactly does it mean when there's no change when bridging the pins on the 'Trinary switch'?

Sorry its a bit of a rambling post but its a bit hard to explain the engine sounding different in a post on here. I did try to do a video, but without a video of how it used to be it's a bit pointless.


All I can think of is the flood water possibly caused a leak in the air con system, and its lost the gas or something?
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Old 16th January 2021, 18:04   #2
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I am on my second gold resistor - first one lasted 5 and a half years. So yours may have failed.
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Old 17th January 2021, 11:50   #3
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It's clear that one of the issues is failure of the radiator fan's low speed system. In trying to operate the aircon, you've effectively run the basic low speed test. The stahdard way to do this is to invoke aircon operation by pressing the demist button. Aircon operation requires the low speed fan to coole the condenser (mounted in front of the engine radiator). If the low speed doesn't run, the aircon system will overheat and trip on the emergency cooling (high speed fan). This runs for a few seconds until the gas pressure is reduced to normal. This cycle repeats until aircon operation is switched off. The fix for this is a replacee,nt low speed resistor. You can source these from traders, electronics outlets and eBay.


From your description, there may well be an unrelated problem with the engine control system. This may be a consequence of driving through flood water.



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Old 17th January 2021, 21:04   #4
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Quote:
Originally Posted by bikerdude666 View Post
What I need some advice on is the aircon ... So what could be the problem cause no drop in revs, no change of engine sound?
Hi Derrick,

From what you've described I don't suspect a fault with your air conditioning. When the compressor engages (both parts of the pulley spinning) it's normal for the engine revs to drop slightly. As you change the temperature display inside the car, the compressor may stop and start at different settings. This is normal.

As T-Cut says though, it sounds as if your resistor has failed.
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And what exactly does it mean when there's no change when bridging the pins on the 'Trinary switch'?
If you tell me the colours of the wires which you bridged I will be able to explain.

Simon
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Old 18th January 2021, 11:17   #5
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Thanks for the replies. I'd assumed it probably would be the resistor at fault for the radiator fan fault, but I hadn't heard of anyone having to replace the gold resistor before. And I was hoping I might find some suggestions for the other issue before doing the resistor, so anything that needs doing with the bumper off can be done at the same time.

As for the engine revs, it did used to drop slightly when turning on the aircon, but now there's no change in revs, and it always sounds like it used to with the aircon on, even with the heater panel turned off completely.

I can't be sure of wire colours, I think when the fan came on it was yellow/grey, and black that was bridged. And I think the others were just red and black, and there was no change or anything.

I'm sure I read somewhere that you should be able to hear a click as the compressor engages for the air con, but when you select air con, and can see the pulley start spinning, there's no audible click or anything.
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Old 18th January 2021, 13:31   #6
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... I hadn't heard of anyone having to replace the gold resistor before.
Hi Derrick,

One or two have "exploded" probably due to water seeping into the cable entry. Arctic always encourages the use of waterproof heatshrink (or equivalent).

Quote:
Originally Posted by bikerdude666 View Post
... I think when the fan came on it was yellow/grey, and black that was bridged. And I think the others were just red and black, and there was no change or anything.
Your memory serves you well. Yellow/grey and black will trigger the fast speed (resistor not in circuit). The only way to check the resistor is by using the windscreen demist function to force the air conditioning to run. However, if you have a separate fault with that, it all becomes rather uncertain.

Don't bridge the red/black & black red because if your air con. is low on gas you might cause expensive compressor damage.

Quote:
Originally Posted by bikerdude666 View Post
I'm sure I read somewhere that you should be able to hear a click as the compressor engages for the air con, but when you select air con, and can see the pulley start spinning, there's no audible click or anything.
  1. Open the bonnet with the engine running and heater in "Econ" mode. Note that the compressor pulley is rotating but the central disc is stationary.
  2. Watch the pulley as an assistant presses the windscreen demist button. You should hear a heavy thunk and the central disc should start rotating. That's the compressor engaging.
If this isn't happening then check that the red wire entering the front of the compressor isn't damaged or wet due to your foray into floodwater. A multimeter is the best way to check for a voltage.

Are you certain that your air conditioning was fully charged and working before?

Simon
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Old 18th January 2021, 19:04   #7
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Quote:
Originally Posted by bikerdude666 View Post
- - - I hadn't heard of anyone having to replace the gold resistor before.
I suspect the immersion of a rather hot fan resistor in 5°C floodwater is a pretty good way of distroying one.

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Old 20th January 2021, 23:34   #8
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Quote:
Originally Posted by T-Cut View Post
I suspect the immersion of a rather hot fan resistor in 5°C floodwater is a pretty good way of distroying one.

TC
Yes I suspect that did it. First flood was just over a blind summit, couldn't see it as it was night, I won't be taking that route if other roads are flooded again!

Quote:
Originally Posted by SD1too View Post
Hi Derrick,

One or two have "exploded" probably due to water seeping into the cable entry. Arctic always encourages the use of waterproof heatshrink (or equivalent).


Your memory serves you well. Yellow/grey and black will trigger the fast speed (resistor not in circuit). The only way to check the resistor is by using the windscreen demist function to force the air conditioning to run. However, if you have a separate fault with that, it all becomes rather uncertain.

Don't bridge the red/black & black red because if your air con. is low on gas you might cause expensive compressor damage.

  1. Open the bonnet with the engine running and heater in "Econ" mode. Note that the compressor pulley is rotating but the central disc is stationary.
  2. Watch the pulley as an assistant presses the windscreen demist button. You should hear a heavy thunk and the central disc should start rotating. That's the compressor engaging.
If this isn't happening then check that the red wire entering the front of the compressor isn't damaged or wet due to your foray into floodwater. A multimeter is the best way to check for a voltage.

Are you certain that your air conditioning was fully charged and working before?

Simon
I couldn't see the pulley properly from the top, so I took the wheel arch liner out and watched that way. Thats what I'd described in the initial post. The central part of the pulley starts spinning when either auto or demist are pressed, and stops when you press Econ or off. But there is no audible sound at all when the central part starts spinning, and there is no drop in revs or change in engine noise.

I'll have to invest in another multimeter, I can't seem to find mine.

I can't say 100% that the air con was working as in, providing cooled air, as it's been so cold lately that just fresh air from outside was as cold if not colder than the air con. However, up until this point the engine revs did drop slightly and there was a change in engine noise when the air con was running.

I've ordered a new resistor for the fan, not sure when I'll get time to fit it though, but once this is fitted I'll at least know that part of it is (hopefully) sorted.
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Old 21st January 2021, 09:35   #9
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Quote:
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The central part of the pulley starts spinning when either auto or demist are pressed, and stops when you press Econ or off.
That's what you'd expect from a working compressor. I wouldn't worry too much about the engine speed. Your diesel will have plenty of spare torque to engage the compressor on a cold January day when it doesn't have to work very hard at all. The next time your windows steam up in the rain, switch on the air conditioning. If it clears the mist after a few minutes you've nothing to be concerned about.

Simon
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Old 6th February 2021, 02:51   #10
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I fitted a new gold resistor today so the low speed is now working on the fan. Once the bumper was removed it was immediately clear why it had failed, 1 of the wires/terminals had completely corroded off!

The radiator behind the fan looks worse for wear, missing a lot of fins, and the intercooler (I think that's what it is, along the bottom at the front...) is also missing some but not as bad as the radiator higher up.

Air con isn't working, despite the compressor appearing to engage, and it still just doesn't sound right. I think I'll have to try and find a local air con specialist to come and have a look at it.

Video of engine noise hear, but its rubbish as it was done on my phone: https://www.youtube.com/watch?v=eWbnXmR-3E4






Last edited by bikerdude666; 6th February 2021 at 02:59..
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