Climate Control

[rigga955]

Does the is200 have full climate control? The reason I'm asking is following on from my air Con not working thread, I've now regassed it with one of those refill cans from Halfords, and its working nicely now and really cold air from the vents, but when its set to auto and the temp dial is on its coldest the a/c cuts in and out as if its reached its desired temp and then cuts back in again ..... is this what climate control does normally as I've not had a car that's had this feature before on a a/c system, just comes on and stays, on but those cars just had a hot to cold dial, not a temperature one.

[ColinBarber]

Yes it does have climate control. Normally on the coldest setting I would expect the AC to be on constantly but it's been a while since I've owned an IS200 so cannot quite remember.

[The Transporter]

If I was to put on my pedantic head, then I would say that no car has climate cotrol as the system does not actually control the humidity other than simply reducing humidity....Even air conditionig is the wrong term but hey ho..... by turning on and off, I'm guessing that you are referring to the compressor cycling on and off... This is normal. on cars like the IS200, the compressor is a simple fixed displacement compressor...... it is either working at 100% or it is off. this is controlled by a temperature sensor in the air strean near to the evaporator (Cold radiator) in the heater box... when the air temperature coming out of the evaporator reaches a certain temperature usually between 2 and 5 centigrade, then the temp sensor will turn off the compressor then when it rises again then the compressor will re engage.... the warmer or more humid the air entering the ventillation unit the longer the compressor will run and the shorter the of time will be...... If the compressor didn't cycle off then the evaportor would get colder and colder, the humidity in the air would freeze on the evaporator, reducing air flow.... eventually to zero, the refrigerant wouldn't evaporate properly in the evaporator and liquid refrigerant would return back to the compressor would pop the valves in the compressor...... On one particularly humid afternoon, I managed to get snow blowing out of the vents of an old Range Rover just for fun

[ColinBarber]

all of this is true but normally when you set the temperature to the lowest setting the system goes on to 'minimum' and will set the compressor on all the time (or at least a very high duty cycle). Maybe this doesn't happen on the IS200 and the compressor is cycled once the cabin temp. is reached.

[petayV8]

It can be on all the time if put on "high" and not auto. The compressor works off the cabin temperature sensor (located under the steering column to the right) so most days in England the A/C wont ever kick in if set to auto

Anyway think of air condition like a fridge, but your car cabin being the fridge. Your fridge's compressor at home kicks in now and again to maintain the temp, on hot days it will have to work more

BTW heard those Halfords A/C cans are pretty lethal and had a look and cost £10 less than a pro doing it, is it really worth the saving?

[The Transporter]

Niet!!!..... The little sensor down by your knee controls the blend flaps which divert the air through the evaporator/ heater matrix depending on what it wants to do (Taking into account information recieved from the solar sensor and the set temperature) The compressor will cycle on and off depending on the temperature of the air coming directly off the evaporator.... Set it to manual and its coldest setting then prettymuch all of the air will be directed through the evaporator and will bypass the heater matrix but the "Air off" sensor will still cycle the compressor on and off if the air temperature is around the cut off point......

Even in the winter the compressor will run irrespective of what setting you have on the dial, provided that the aircon is switched on.... It will cycle quite rapidly but it will still run and cool the air.... unless the ambient temperature drops below about 4 or 5 degrees where the vapour pressure of the refrigerant will drop below around 30 psi and the system pressure switch will shut down the compressor untill the ambient air temperature increases or the vapour pressure of the refrigerant exceeds 30 psi..... so if the evaporator is warm due to being inside the car then the system can run when the ambient air temp is below 5 but only once the car has warmed up...

I used to love those top up cans, they made me lots of money from wrecked compressors....... to correctly charge a system you must first apply a vacuum... if you leave air in the system then it doesn't condense like the refrigerant and when the heat is on your compressor is working harder and using more fuel to cool you than it should..... it also puts a lot of strain and undue pressures on the components.... Also some of these top up cans contain a lot of lubricant and other stuff.... too much lubricant reduces the efficiency of the cooling sysem and also if you really overdo it then you can have a situation where the compressor gets slugged with great gobs of liquid lube which cannot be compressed and will damage the compressor....

[rigga955]

Thanks for all the reply's, now I know it was just lack of gas that was stopping the system from working I can always get it vacuum and refilled correctly, £17 for the Halfords can to confirm that was ok for me.

[The Transporter]

Thick Fit used to do a no fix no pay thing on aircon recharges.... Not sure if they still do..