Problems with climate control

[ultimagtr-ger]

Hello,

I really love my GTR.With the longer gearing it is fantastic on the German Autobahn. I did make one day trips with about 1.000 miles which was great fun.

BUT I hate that on long journeys on really hot days (> 30 degrees Celsius) the climate control is suddenly not working and we are feeling like baked potatoes.

Situation:
After fast driving some hours it is suddenly getting hot in the cabin. The control knob (under the dash) is still set to full cooling position (on).
I move it to no cooling (off) and back to on. With the typical click noise from the compressor clutch I can hear the climate compressor should start but still only warm air comes out of the vents.
After turning off, waiting at least 10 minutes and turning on again cold air is produced for a few minutes and then only warm air comes out again. This is not chainging till I turn off the climate controll, wating at least 10 minutes and turning on again. And so on.
I don't want to concentrate on turning off and on the climate control while driving 200 MPH.
Water (or whatever) is dripping down on the legs of my passenger.
On the next (cooler) day all is working again aus usual!

I assume that the pressure is getting too high and/or not enough heat can be transfered from the climate cooler (in the side pot).

My idea to resolve the problem:
I would like to turn off the climate compressor if the pressure is getting too high with a pressure switch. Hopefully the compressor will be off only for a short time and working back again faster than now (and automatically).

Where should I place the pressure switch?
On which pressure the switch should turn off the compressor?
Where can I buy a pressure switch?
Is there an other solution for the problem?

I really appreciate your help.

Thanks

Regards
Oliver

Edited by ultimagtr-ger on Monday 27th July 10:30

[San Diego GTR]

Oliver,
I assume you're using the stock AC setup that is supplied by Ultima. If you can hear the compressor clutch engaging, it might be a couple of other things. Lets assume your using the proper 800 grams or 28 oz of refrigerant. Your pressure switch may be malfunctioning or your condenser isn't cooling the refrigerant enough. I would guess the issue is with the condenser as you can turn it off (letting the system and the refrigerant cool off) and then successfully start it back up again for a few minutes. I had to replace my brand new pressure switch so check that to be sure. I chose to replace the 12"x18" serpentine condenser with a 12"x24" parallel condenser. The larger surface area obviously adds significantly better cooling capability. I also added a fan shroud which provides for more air over the entire surface of the condenser. Finally, after some fiddling, the system works great now. In fact it is way too cold to have on for long. I'm still working on the dripping over the passengers feet however. Good luck, Paul

[GTRCLIVE]

ultimagtr-ger said:

Hello,

Water (or whatever) is dripping down on the legs of my passenger.
On the next (cooler) day all is working again aus usual!

I assume that the pressure is getting too high and/or not enough heat can be transfered from the climate cooler (in the side pot).

My idea to resolve the problem:
I would like to turn off the climate compressor if the pressure is getting too high with a pressure switch. Hopefully the compressor will be off only for a short time and working back again faster than now (and automatically).

Where should I place the pressure switch?
On which pressure the switch should turn off the compressor?
Where can I buy a pressure switch?
Is there an other solution for the problem?

I really appreciate your help.

Thanks

Regards
Oliver

Edited by ultimagtr-ger on Monday 27th July 10:30

Hi, sounds like a problem with the system as it should run fine.

1. The Condenser is not cooling the Gass enough (Check the Condenser fan comes all the time the AC is on)
2. The "Evaporator Coil" (Heat / Cooling under-dash unit) is freezing up and becoming a Block of Ice. This can be caused by the Anti Frost Switch not working properly, is the Temp Dial unit have the Capillary tube Probe pushed into the Coil Area ?? if not that will cause a problem Coil Freeze up.


You can see the Small Silver tube above the high lighted line that's goes from the Temp Knob thought a Hole in the side of the AC Unit and into the Coil area.
3. If it's not freezing up like a block of ice then the Expansion valve may be faulty, that's the
Valve that's bolted In-line to the Small hose on the inlet to the AC unit. Also the small capillary tube from that valve may not be placed correctly on the Copper inlet tube...


On a side not there is a Switch that's on every AC system that turns the Pump On and Off when there's to much or not enough pressure in the system, its on the top of the Liquid receiver, some times called the Filter Drier. Its the black Steel tube on the bulk head.

4. Last but not least is the System Charged up enough ??? I'm guessing that's the first thing you checked but better check that first.....

and are the Drain hoses connected up ?? there are 2 small tubes sticking out of the AC unit at the bottom that should be connected to some hoses that will drain the Condense away, not dripping on the passenger floor.....

Email me if you still can get it working

[GTRMikie]

GTRCLIVE said:

Also the small capillary tube from that valve may not be placed correctly on the Copper inlet tube...

This small capillary tube must be well insulated from the surrounding "air" so that it accurately detects the temperature of the copper inlet tube it is clipped to. The aircon kit comes with a small piece of sticky black tape for this purpose, but I wrapped mine with some sticky foam tape which is much more efficient. I also wrapped the metal coolant tube ends with it to stop condensation forming and dripping into the foot well and, as Clive says, make sure your condensate drains are working properly!

[ultimaCZ]

Hi,
I can offer different solutions (having faced exactly the same problem, and got rid of it):
1. Could be too much gas in the system; I reduced to 400-450 grams (but I am using a different, a bit smaller condenser from a Porsche 911) and it worked much better, did not switch off that often
2. Override switch for the cooling fan; On a hot day I leave the fan switched on, because otherwise it is also switched on/off when the clutch engages/disengages (at least that is what I remember)
3. most importantly: the heating valve on my Ultima (factory build) was never closing 100% (and it is just on one line, dont know whether to or from the engine), which means that when the engine is hot anyway some hot water is going through the heater pipes, meaning that the air condition is working against the heater (at least that is my theory, I have no evidence, though). We installed a manual close-off valve in the heater lines close to the engine, which is switched off during summer, now it is much better and when I switch off A/C then no longer hot air is coming out of the vents in the cabin
Hope that helps,
Peter

[V8 Vum]

Hi Peter,

Hope all is well with you....

Your 911 condenser, is that the complete heater/condenser/fan unit?
How easy was it to fit in place of the Ultima one?
Because the dash on mine is having major surgery I am having Gods own trouble with space and wondered if your solution would help. Any piccys on the install?

Cheers

Keith

[ultimaCZ]

V8 Vum said:

Hi Peter,

Hope all is well with you....

Your 911 condenser, is that the complete heater/condenser/fan unit?
How easy was it to fit in place of the Ultima one?
Because the dash on mine is having major surgery I am having Gods own trouble with space and wondered if your solution would help. Any piccys on the install?

Cheers

Keith

It is just the condenser, which is smaller than the Ultima unit, to make place for other parts which we installed in that area (fuel swirl pot etc.). All other A/C parts remained original Ultima.
The install of the new condenser required some welding/customising, which worked well, once we found somebody who was willing to do that

Edited by ultimaCZ on Tuesday 28th July 11:47

[Untamed_Muscle]

First thing that caught my eye was the fact that he is going almost 200mph when the A/C unit isn't wanting to work. Wouldn't he most likely be at WOT to stay at that speed, and wouldn't the A/C be auto shut off at that speed as well?

[Steve_D]

Untamed_Muscle said:

First thing that caught my eye was the fact that he is going almost 200mph when the A/C unit isn't wanting to work. Wouldn't he most likely be at WOT to stay at that speed, and wouldn't the A/C be auto shut off at that speed as well?

The factory supplied system does not have a speed cut-out.

Steve

[Untamed_Muscle]

Ah, I stand corrected. Thanks Steve

[lordburham]

If the system is undercharged with refrigerant the evaporator will ice up and produce loads of condense and will also trip out on the pressure switch (LP). If the system is overcharged then on warmer days it will also trip out on the pressure switch (HP)

[ultimagtr-ger]

Hello,

Thanks to all for the interesting information.
I will controll the climate compressor clutch with my PCM.
I will turn it off on full throttle and over 4.500 rpm.

I will go to a garage to check if I have 800 grams refrigerant.

I'm using the Ultima standard parts.
Where can I find the LP pressure switch and the HP pressure switch?

Thanks
Regards
Oliver

Edited by ultimagtr-ger on Thursday 30th July 15:56