[Marko_SJ]

Hi Auszookers looking for a bit of advice here, any 2 cents is appreciated.

Problem: My sierra has dealer fitted aircon, but it is now faulty.

Over time because of the way the wiring was laid out under and through the dash, being bent and mechanical load placed on it etc.. it does not seem to be sending power to the A/C clutch, I came to this conclusion because the clutch 'clicks' when you bridge it to the battery terminal, and taking readings with switch on and off.

The compressor runs when you 'tweak' the wires, the condenser fan works too (the whole time).

So my questions are: would it be OK to run a power lead straight to the compressor with an on/off switch?

Would I risk compressor damage by running it flat out? Should I pull the dash (again) and make a complete new loom like I was going to?.

I'm getting a bit sick of the humidity and getting 'the full experience' when I have to drive past the sh*t farm!

Cheers,
Mark

[fordem]

That depends on WHY the compressor clutch is not being energized, the fact that the condenser fan runs "the whole time" suggests that the a/c controller may be detecting a coolant overheat condition, which will cause it to disable the compressor and enable the fan.

The a/c controller typically includes several "fail safe" mechanisms that de-energize the compressor clutch, for example, if low or high refrigerant pressures are detected, if the evaporator freezes up and as mentioned if the engine coolant over temps.

[MacDaddy]

The_Amateur wrote:

Hi Auszookers looking for a bit of advice here, any 2 cents is appreciated.

Problem: My sierra has dealer fitted aircon, but it is now faulty.

Over time because of the way the wiring was laid out under and through the dash, being bent and mechanical load placed on it etc.. it does not seem to be sending power to the A/C clutch, I came to this conclusion because the clutch 'clicks' when you bridge it to the battery terminal, and taking readings with switch on and off.

The compressor runs when you 'tweak' the wires, the condenser fan works too (the whole time).

So my questions are: would it be OK to run a power lead straight to the compressor with an on/off switch?

Would I risk compressor damage by running it flat out? Should I pull the dash (again) and make a complete new loom like I was going to?.

I'm getting a bit sick of the humidity and getting 'the full experience' when I have to drive past the sh*t farm!

Cheers,
Mark

Hi Mark,
If the compressor runs, ( clutch engages ), when you tweak the wires, then it sounds like you have a wiring/connection fault... the condenser electric fan, should come on, and stay on, when A/C is turned on, so thats ok...
Best not to run a wire to just a switch, better to trace the compressor wire back, and find where the fault is, yeah its a PITA, but its the best way...
The compressor is designed to run continuously, most people put the thermostat all the way into the cold ( Blue ) on the temp switch anyway, which will keep it running, but, it is designed to run at optimum within certain design specs, under certain conditions, so if they arnt met, it will shorten the life of the compressor, which is why it has safety switches to shut it off...
So yeah, short cuts, to get it to work, arnt the best, and may end up being a more expensive fix...

[Marko_SJ]

Thanks fordem and MacDaddy for your replies they are appreciated,

I forgot to mention that this would be after I had the refridgerant gas checked by my mate, and if it still played up.

But anyway, I will take your advice onboard and will do it properly after I get it checked out, looking at the condition of the loom its all pretty suss.

Oh well, cue more 'project'.

Mark

[royce]

Compressors dont run all the time, they run till the pressure is high enough then stop, macdaddy I thought you were a fridgy once?

dont bridge anything, pull the harness out (it will be seperate to the car loom) and trace it out and find the breaks in it and go from there
Normally the fan runs with the compressor, it could be the system wants the compressor on and power jsut isnt getting but its getting to the fan, they both might be switched by separate relays, find them and test if they should be on and why they arent, its going to be hard to work out unless you understand woring and how AC works with the pressure switches and so on so your choices are either start googling to understand it or pay somebody to fix it for you

[Marko_SJ]

Thanks Royce,

It is currently running R-12 which my mate and his old man don't have, so I might get the gas checked/changed to the new stuff by an auto air conditioning shop and then go from there.

The bodgy section of wiring seems to be the bit that comes straight out of the control box or A/C amp as the yanks are calling it, so I might be making a new A/C harness.

Mark

[mrw82]

Could be that if its low on gas the low pressure switch isn't letting the compressor start? Have you had the gas checked?

[MacDaddy]

royce wrote:

Compressors dont run all the time, they run till the pressure is high enough then stop, macdaddy I thought you were a fridgy once?

Quite a few older cars, pre 2000, ( which is what i worked on ) dont get cold enough in cabin, for them to cycle on and off, and alot of people dont know to switch it from vent to recirculate, and close the windows, ( had to educate quite a few people about this ) so with those factors, yes they can run all the time... but, if the " superheated vapor " pressure gets to high, without enough cooler airflow thru the condenser, like when sitting at traffic lights on 40+c days, the high pressure cut out will activate, and stop it running for a while...
Modern car A/C systems, will cycle on and off, no matter if the temp control is all the way in the blue, and are alot more efficient... yep i am fridgy, thats my trade... but... i havnt done any major fridgy work for 15years, still do the odd job, so not fully up to date on the newer car A/C systems...

[Marko_SJ]

Ended up having someone check the refridgerant. There was plenty in there and no sign of leaks which I was very relieved to find out.

They also cleaned the evaporator which was partially blocked, as can be expected with a 25 year old sierra. I will pull the dash over the weekend and start getting parts needed to make a new wiring harness and I have a feeling that should be it.

Thanks for all your advice.

[jimbo_jones]

Wish I could find a a/c system for my zook

[Marko_SJ]

Due to laziness and sierra driver-ness I never made up the new loom.

Strangely it started working well shortly after the last reply to this post, and still does. Now the A/C switch on the dash has died.

Any recommendations on where to find a replacement?

Cheers guys.

Mark

[johnmath]

Quote:

Strangely it started working well shortly after the last reply to this post, and still does. Now the A/C switch on the dash has died.
Any recommendations on where to find a replacement?

If it looks like SW0027 or SW1024 you could email theses guys for a price: http://www.polarbearinc.com/pbpc/homepa ... rt_SW.html

[Marko_SJ]

johnmath wrote:

Quote:

Strangely it started working well shortly after the last reply to this post, and still does. Now the A/C switch on the dash has died.
Any recommendations on where to find a replacement?

If it looks like SW0027 or SW1024 you could email theses guys for a price: http://www.polarbearinc.com/pbpc/homepa ... rt_SW.html

Cheers mate.

It looks a bit like SW0027.

[sideways]

Pull the switch apart and rebuild it.

[Marko_SJ]

sideways wrote:

Pull the switch apart and rebuild it.

Haven't got much to lose I guess.

Actually doing something is the hard bit though.

[rob45x]

How'd you go with this problem?
I've got a question about ac in my sierra
It's an r12 system but I can't find both the high and low pressure ports to re gas. I can only find one. I retrofitted it with an adapter and re gassed it. But leaked after a little while. Anyone Know where the other port is located?

[shandy92]

Prob system unique, follow a line from the evaporator to the comp and it should be there somewhere.

[EX ONE]

Hey I have 92 sierra and I want to install air conditioning. How does one go about doing this? I don't know a lot but I'm trying to do as much as I can myself. Are there air con kits I can buy or can I just get one from a vitara and put it in? Is there a place where I could get instructions to do this?

Thanks heaps for any advice.

[bumstein]

There’s plenty of Sierra air con setups that pop up for sale, put an ad up in the WTB section and/or gumtree and see what pops up.

As for installing, can’t help you there I’m afraid. Some else will no doubt be onto it

[laager]

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[sideways]

I looked at knee freezers like that for mine. Imo they just rob to much knee room, the passenger's seat would be just about unusable. You might be able to gut one and fit it up behind the glove box which would be fairly slick.

The factory/dealer fit setups just run the evaporator right into the intake of the heater box, it would be quite easy to replicate. You could run whatever condenser you want and 3d print an adaptor to the heater box.

[laager]

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[Gwagensteve]

They pull very high current though, which you have to generate via the alternator and it’s likely that the alternator won’t deliver enough current to meet the demand at idle/low engine speeds.

[laager]

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[Gwagensteve]

Yes, but “presuming you have enough power to run it” presumes it’s easier to set up a big enough charging system to run the electric compressor than it is to fit a belt driven compressor as the factory did.

Additionally the losses involved in generating the power via an alternator and then storing and transporting that power to the compressor mean the whole system is less efficient than a belt driven compressor.

I understand the appeal but for a small engined light vehicle (with a comparatively small and light charging system) I don’t think these remote compressors are all that appealing.

[laager]

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[Gwagensteve]

You seem to be very defensive about this issue, I don’t think there any reason to be so aggressive, on top of that you seem to be missing my point.
Upgrading the charging system of a sierra to suit an electric AC compressor in addition to any other electrical load is a substantial undertaking. My argument is it’s more expensive and complex than utilising the parts that already exist to fit a belt driven AC compressor

Of course Suzuki fitted the smallest and cheapest charging system they could for the application. I’m not challenging that, I’m challenging the advantage of running an electric AC compressor compared to a “factory” belt driven compressor based on cost and complexity vs perceived benefit (packaging? Is there another benefit?)

Below about 1500rpm the most I’ve seen an EL/EF alternator deliver is 46A. I don’t believe that will provide enough headroom to run an electric A/C compressor on top of other accessory load. The duty cycle of an AC compressor is quite high and is irrespective of engine speed.

I think these systems are viable where no factory based parts exist or can be made to fit (such as home built by Jeff’s Ferrari powered Alfa) but where complete factory A/C systems fit and are available I can’t see the advantage.

[laager]

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[Marko_SJ]

I doubt my original issues had anything to do with the loom and I should have done what Royce said and paid someone.

I ended up getting custom brackets made to run power steer and AC. Worked great mechanically until farmer logic saw the condenser cut out with a grinder.