How Cold is Cold? - Anglesey Ian
Hi all.

I have recently purchased an immaculate Saab TiD (2100cc+17000miles of vintage Feb 2001) and am very pleased with it. A distinct difference to my old VW petrol Vento. It is fitted with an AC unit and, before you ask, I don't know whether it's fully air conditioned or fitted with 'climate control'. I should know the difference but I'm afraid that I don't so there it is! (It has no thermostatic setting control)

Having read recent contributions to backroomland about AC, I have been dutifully running the AC system regularly to keep parts lubed and servicable. I have also noted that some contributors have run their systems to being 'uncomfortably cold'.

With the recent spell of warm (if not hot)North Wales weather, I have been using the AC by comfort choice and not for routine and the car does not become very cold: just chilled.

Can anyone advise if this about right or whether I need to get it fixed whilst still under warranty. I know that my description is hardly scientific but any advise would be appreciated.
With thanks


How Cold is Cold? - SkyMan
The effectiveness of aircon varies from car maker to car maker e.g. my wifes Toyota cools down quicker than my Nissan.

I had a problem with mine when I bought the car (the TX valve had failed) - when the mechanic checked the system after fixing it he held a temp sensor near the air vent and had the aircon on full "Cold" (got climate control). Once the reading got to 7deg he was happy with the fix.

BTW - he said that Toyota's (at least the imported types we get in NZ) can get as cold as 5deg at the air vent)
How Cold is Cold? - Anglesey Ian
Thanks SkyMan for your prompt response !

Don't go all technical on me just yet . Could you please advise what a TX valve is ?

You're quite right of course, in that my question would have been more professionally valid and with more integrity if I had been able to quote a temperature at the outlet vent.

I'll take a reading tomorrow and let you know.

Diolch yn fawr/thank you


How Cold is Cold? - SkyMan
To be honest, I'm not sure what a TX valve is either!!! Whatever it was it cost me NZ$250 to replace though.

Sorry if it seemed I was knocking your question - it was 7.30am here when I typed the reply :)

Basically if I were you I'd turn the aircon on, with full fan whilst driving (so that the aircon compressor is spinning at a good rate) and hold your hand in front of one of the vents. If it gets cold enough that you really notice it (i.e. like a frosty Brit morning) then I'd say your aircon is working fine.

You could also get the pressure tested at an aircon-equipped garage - in NZ the test is usually free (but they try their hardest to find a fault)

How Cold is Cold? - Dave N
The TXV is the thermal expansion valve. It's job is to meter the flow of refrigerant into the evaporator. Too much and it gets flooded, and proper evaporation doesn't occur. Too little, and it all gets vapourised instantly and without removing any heat.

When they fail, they either get stuck open or closed (usually closed).

The lowest the evaporator can get is zero degrees, otherwise all the condensation would freeze and you'd have a solid lump of ice under your dash. So the system tries to keep it at about 2*. Therefore, after a bit of heat gain as it travels along the ducting, you will usually end up with 5-8* at the vent.

But the ultimate temperature isn't terribly important, as long as the system has the ability to maintain sufficient cooling. Look at it this way, if you want to cool something down from 30* to 15* by putting it in the fridge, it doesn't make a lot of difference if the fridge is 5* or 8*.
How Cold is Cold? - Miat
is this correct ?

i know for sure hire cars in the states i can turn temp right down in a heat wave and cause frost to form on the front window! comfortable for me, but had to turn it up a touch to be able to see out - therefore must be lower than zero ?

never seen a UK car with air con that powerful

always assumed they put different power systems into different markets ?
 

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