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Discussion Starter #1
Hi

sounds like another fault.... what temp does other peoples rad fan cut in at?
mine will creep all the way up to the top of green before cutting in which i think is a little too hot!

Also i think i have block in climate control system, condenser works but no wouldn't charge up? any ideas.

Cheers
 

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el-tel said:
Hi

sounds like another fault.... what temp does other peoples rad fan cut in at?
mine will creep all the way up to the top of green before cutting in which i think is a little too hot!

Also i think i have block in climate control system, condenser works but no wouldn't charge up? any ideas.

Cheers
Apparently the later cars have a placebo gauge that doesn't really help you much and doesn't report the temperature from a sensor on the head. Not sure where is good and where is bad.

I don't understand what you mean about the climate control system. The condensor is the radiator type bit, there's nothing to see "working" and nothing charges up as such.

Are you referring to the compressor? Does the compressor clutch engage rather than just the pulley spin? in other words does it do this:-

Compressor clutch action

If it's not engaging or is running in short on/off cycles then that suggests low pressure of the gas - get it re-gassed.

If it's working in longer cycles and the larger of the two pipes along the top of the inner wing is ice cold with condensation on it then it could be that the mixer flap isn't closing properly and so you're mixing warm air from the heater.

Does the engine cooling fan come on regularly too? It should do when you've got the AC turned on.

David.
 

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Discussion Starter #3
hey bud


it is a 94 Aero. Air con would not charge up and i have been told there may be a block in the system. The rad fan cuts in late so i think this could be the temp sensor on the head which i shall replace.
The fan doesn't seem to cut in regularly either when climate control on, it usually switches onto auto anyway.

hope this might help.

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el-tel said:
it is a 94 Aero. Air con would not charge up and i have been told there may be a block in the system. The rad fan cuts in late so i think this could be the temp sensor on the head which i shall replace.
The temperature sensor for the radiator isn't in the head, it's in the lower left of the radiator as you stand at the front of the car. The one in the head just provides display to the gauge although I believe that the 1994> is a little different in this respect for the gauge.

The fan doesn't seem to cut in regularly either when climate control on, it usually switches onto auto anyway.
The fan won't cut in if there's nothing in the AC system, there's no need because the gas isn't hot because there's no gas! :)

I'm puzzled about the suggestion that it may be blocked though, I guess it could be but it's a pretty open thing after all, just a load of pipes, an expansion valve and a compressor. Have you tried providing power to the compressor clutch directly to see if the compressor runs? If it does don't run it this way, just test it although again, this is pretty pointless if there's no refrigerant in the system.

Have you tried a second opinion on the AC system?

David.
 

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Discussion Starter #5
should be gettin someone to look at air con next week, for another opinion.

The condenser working fine, but told there could be a block in the dryer, (black thing lower left of condenser) or in the actual air con rad.

The fan cuts in but not early enough according to Turners Hill SAAB and they suggested the temp sensor on head as that works with guage and also sends info to switch fan on somehow.

Cheers
Terry
 

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el-tel said:
should be gettin someone to look at air con next week, for another opinion.

The condenser working fine, but told there could be a block in the dryer, (black thing lower left of condenser) or in the actual air con rad.

The fan cuts in but not early enough according to Turners Hill SAAB and they suggested the temp sensor on head as that works with guage and also sends info to switch fan on somehow.

Cheers
Terry
The 1994 EPC still shows a "thermo contact" in the radiator for the radiator fan switching but hey, I have a 1993.

I think you're confusing compressor with condenser. The condenser is behind the grill, looks like a radiator (because that's pretty much all that it is). The compressor is the pump that is turned by the fan.
 

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Discussion Starter #7
Thanks again for your help, found out that the ACC Condenser is pretty much mullered so will get new one, also air con man said the drier too, any ideas where this is?

Also with the rad fan problem it is only cutting in on high speed at top of green. I have been told it should come in at a lower temo or with acc at a slower speed. I have a new rad fan switch but while i was installing it i found that one of the wires on the connector had corroded and come apart on the loom end, i have re-attached this to the wire on the fan switch but still no joy at the moment. I also checked for feed through resistor on fan shroud and there is power running trough.

Any more suggestions????

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el-tel said:
Thanks again for your help, found out that the ACC Condenser is pretty much mullered so will get new one, also air con man said the drier too, any ideas where this is?
I'm really puzzled, how can he say it's the drier without any apparent investigation? It's down behind the offside headlight.
Also with the rad fan problem it is only cutting in on high speed at top of green. I have been told it should come in at a lower temo or with acc at a slower speed. I have a new rad fan switch but while i was installing it i found that one of the wires on the connector had corroded and come apart on the loom end, i have re-attached this to the wire on the fan switch but still no joy at the moment. I also checked for feed through resistor on fan shroud and there is power running trough.
There are 2 relays in the box by the battery, one for high speed, one for low speed. All the resistor does is drop a bit of voltage to the motor, the rad switch energises the relays accordingly. It could be a sticky relay or other broken wire somewhere. If the fan turns at high speed it's nothing to do with the resistor unless that has burnt out but you should be able to identify that pretty easily looking at it.

David.

Any more suggestions????

cheers[/QUOTE]
 

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Discussion Starter #9
the bloke diagnosed the drier/evaporator and condnser after spending about an hour working on it, he said system charged but wont stay that way for long and as the drier not functioning properly sometimes i get cool air or others warm. but at least the compressor workin ok.

I will try changing the relay, i did this yesterday but this was before i found the damaged wire. Other wise i shall change the rad switch and if still no luck then maybe an electrician!

thanks
 

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Have looked at the thermostat? It may be jammed in an almost shut position and not passing enough coolant.
 

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This is where i'm still confused! The drier, the evapourator and the condenser are three totally separate items. He has diagnosed that they're all faulty?

The condenser is just a long pipe with fins, the evapourator is just another long pipe with fins (zigzagged to save space) and the drier is a bottle with a dessicant to absorb moisture, no moving parts and the drier doesn't have anything to do with cooling the air.

Changing the radiator switch won't help, you have an issue with your air conditioning do you not?

Maybe it's just me but is this a second opinion or the further opinion of the first guy because I wouldn't have any faith in someone who is "diagnosing" three totally seperate parts that each have unique functions and saying that they're all faulty.

Earlier, you said it wouldn't take any gas, what state is it in now? Is it re-gassed with the correct amount (950g) of refrigerant? Why does he say it won't stay charged for long? Has he found a leak? Where's the leak, what needs fixing?

You need to offer much more info, i'm afraid i'm finding it very incoherent right now with different tracks. You've now brought the speed of the cooling fan into the mix which wasn't there before.

Can I have the answers to the following:- :)

1. Is the sytem regassed now? Is there a leak, if so which bit, was dye used to find it?

2. Please time the on/off cycle time of the compressor clutch and report back.

3. At what point does the cooling fan come on when the ACC is on, please do this with the engine cold so that you don't get confused with the engine temperature. The fan should come on pretty soon after the ACC is turned on.

4. Is the air from the vents cold at this point?

5 What about the system operation from above is different when the air vent air is warm? Is it that the compressor has stopped compressing? Is it that the cooling fan is no longer cycling?

Air conditioning is very simple in operation, the only moving part with any excitement is the compressor. You might find this helpful

David.
 

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Discussion Starter #12
Right sorry.

I'll start again....

The second guy i got to do air con re-filled the gas and told me it would not stay in for very long, the lower section of the condenser is very badly damaged. He also said that it needed a new drier... but i did not find out if it was due to a leak or just not functioning but this also isn't in particulaly good cosmetic condition so i can find out by calling him....(the car was off the road for 5/6 years)

The cooling fan does not come on when the acc is on. Only time this works is when the temp gauge is at the top of green. So no slow speed.

I was going to change the thermostat but have not yet and also the the thermo switch on head, but couldn't see the point in doing the later.

Thanks again.

Terry
 

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el-tel said:
The second guy i got to do air con re-filled the gas and told me it would not stay in for very long, the lower section of the condenser is very badly damaged. He also said that it needed a new drier... but i did not find out if it was due to a leak or just not functioning but this also isn't in particulaly good cosmetic condition so i can find out by calling him....(the car was off the road for 5/6 years)
This still bothers me. He is saying that it won't stay gassed long based upon what? A visual look at the condenser? Did he fill it with nitrogen to see if it leaked? Vacuum it and see if it held vacuum? Did he add dye so that you can see if it does in fact leak?

My questions are still unanswered about the operation of the compressor though, unless i've missed it. Are you saying that the compressor clutch engages? What cycle times?

The drier would be changed as a precaution but it's not a "working" component, it just has dessicant like you get in the little sachets in a box of shoes, the stuff to absorb moisture.

The cooling fan does not come on when the acc is on. Only time this works is when the temp gauge is at the top of green. So no slow speed.
This is potentially bad because the temperature of the refrigerant rises very rapidly and the high pressure switch should cut in the engine cooling fan. Please understand that this has NOTHING to do with the temperature of the engine so lets not bother about that right now. You need to check the operation (electrically) of the high pressure switch and relay and it should come on at high speed anyway. Did either of the AC guys connect up the gauges to the high and low pressure side? They don't sound like the most clued up A/C chaps to me still.

David.
 

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Discussion Starter #14
He carried out a nitrogen checkand it showed condenser is at fault. said that the clutch on the compressor was engaging correctly too. (i also asked saab about that and they said it wouldn't come on if there was not enough gas in the system though) not sure on cycle times though.

Where abouts is the high pressure switch for the cooling fan? I was unable to go through everything with the ac man as it was being done while i was at work so i do not know if he connected up to test these switches. I will try and find out from him tomorrow though.

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AC system needs to be leak proof before you try to diagnose anything else. If the condensor is leaking you need a new one.


The AC system hs to be systematically troubleshot or you just go round in circles.

Basically: the compressor driven by the engine pushes compressed refrigerant into the condensor, which is then cooled by the airflow down to close to ambient (which might be quite warm actually). The compressor builds pressure to a certain level, then the expansion valve opens and allows the cooled compressed refrigerant to enter the evaporator. The expansion valve often fails and the system will then over pressure and cease operating. The evaporator allows the refrigerant to expand and reduce pressure which is what provides the cooling. The air passing through the evaporator transfers it's heat

There is a lower and upper limit pressure switch usually on the end of the dryer. This prevents the system from operating if the pressure is too low to cool or too high to operate safely.

There is an anti frost switch that will not allow the compressor to operate if ambient temperature drops to around 3 degrees C (or 40 F) and then cuts back in at 5 C usually. This prevents the evaporator from becoming blocke dby ice due to water vapour in the incoming air freezing on the evaporator.

Test the radiator fan switch by shorting the terminals with a screwdriver. The fan will turn on. If you do this when the engine is hot enough that will tell you that the switch is to blame. When the engine is cool it tells you nothing. Because the rad fan turns on I suggest the rad switch is OK.

The likely fault is the low speed fan resistor or relay ( I'm not sure which is the method SAAB uses) for the two speed fan, if it is two speed. the older SAABs used a single speed fan and a second fan for the AC and for extra cooling if the engine got too hot. later cars use a two speed fan i think, the AC circuit should turn the fan on as well as the cooling circuit.

The temp sender in the head does not do anything about the fan, it only sends to the dash gauge.
 

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Superaero said:
The likely fault is the low speed fan resistor or relay ( I'm not sure which is the method SAAB uses) for the two speed fan, if it is two speed. the older SAABs used a single speed fan and a second fan for the AC and for extra cooling if the engine got too hot. later cars use a two speed fan i think, the AC circuit should turn the fan on as well as the cooling circuit.
The UK models don't have a seperate AC fan, only turn on the single fan on the high speed so the resistor is out of the loop for this, hence the probable culprit would normally be the relay.

But I agree, there's no point doing anything with it if there is a diagnosed leak.

David.
 

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Discussion Starter #17
Thats cool,
i have new condenser and drier on way, so once fitted and re-charged i shall see if problem persists.
Do you know if there is another relay behind main fuse box in glove box for the rad fan? As i have canged one in the engine bay but i have another that i will also try.

Cheers
Terry
 
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