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Jan 15, 2017

Air Conditioning, AC, Heater Troubleshooting, and Diagnosis for Nissan Skyline GT-R

Old cars.  R32, R33, and R34 Nissan Skyline are old cars. 25, 27, maybe 30 years old by the time you get around to needing this guide. Parts don't last forever.   The cars all used R12 refrigerant, which you know is harder to get than legal cocaine. R12 has been phased out of the US since 1996. It was replaced with R134a, which now seems like it might also be ending life on earth, so something new will probably be the latest greatest refrigerant that doesn't kill everyone in a week.

R32 GT-R A/C control panel pulled out of the dash. 
A/C systems are fairly complex, as they have a lot of parts. They are mechanical, electronic, and they have gases under high pressure.  They really aren't for the novice to automotive repair.  Generally we would recommend taking the car to an A/C repair shop to discharge, or recharge the system. While the Nissan Skyline may never have been sold in the US, the parts of the system are very similar to other models sold in the US.

R12 fill. 0.75-0.85kg for R32

R33 GT-R R134a fill, and recommended oil for AC

R34 GT-R R134a fill, and recommended oil for AC


The first thing to try, is just cycling the unit. Turn it on, go from heat, to A/C and change the recirc settings. See if this frees anything up. Sometimes the doors stick, and just cycling it will help to make everything work again.

Check Fuses.

A/C Clutch fuse is 10A top row, 4th from right R32 GT-R

After that, there is a way to put the A/C into diagnostic mode.  What you do is hold down the OFF button on the A/C unit while starting the car. Continue to hold the OFF button down, until all the lights on the A/C unit light up. It is now in diagnostic mode. If you let it go early, you have to turn car off, and try again.

The flowchart

For complete troubleshooting, download the R32 service manual, and hit up the HA section.

GT-R Groan

Does it sound like you have a monster in your dash?  Do you have to explain what is going on when cycling though A/C or heater settings?

It is probably this A/C mode actuator. The gears in the unit get worn out, and they emit a pretty bad sound. There are several available on ebay here.

This same actuator is used on nearly all the R32s, 2 and 4 doors.  Also S13 88 up. B13 92 up. J30 88 up. Etc


Blend Door Actuator or Air Mix

27730-01U00 - Actuator Air Intake Box - Early cars

27730-01U00 Actuator Air Intake Box - Early 2 and 4 door. Including GT-R
27742-77S60 - Actuator Air Mix

This one also looks like it works with early cars. Including GT-R

New A/C Compressor for Nissan Skyline GT-R

Brand new R32 GT-R R12 A/C compressor
If your A/C is blowing fuse #5, it probably has a bad A/C compressor clutch. If you need a new compressor, they are available here.

92600-05U14 Compressor - cooler - R32 GT-R
92600-24U07 Compressor - cooler R33 GT-R
92600-AA301 Compressor - cooler R34 GT-R

Condensor, compressor, lines, dryer, and other parts. via FAST

Evaporator, located inside car, behind glovebox via FAST

Expansion Valve

A 1990 Nissan 240SX expansion valve works.
An expansion valve is an AC component that is commonly found on many road going vehicles. It is usually installed at the evaporator inlet and works together with the orifice tube to regulate the flow of refrigerant through the vehicle’s AC system. Too much refrigerant flow and the evaporator core will freeze over; too little and the evaporator core will overheat and compromise the efficiency of the AC system. The expansion valve meters refrigerant flow according to evaporator temperature and the load and cooling demand of the AC system.
Conversion of R32 GT-R from R12 to R134a.

This is the cheap and dirty way to do it. A much better and more expensive way is to replace all the hard parts, condenser, compressor, and recharge with R134a.

Old A/C dryer

The old oil in the system needs to be flushed as it is not compatible with R134a oil

Old dryer replaced with R12/R134a compatible part

O-ring replaced

R134a high pressure fitting replaced

O-rings replaced

O-rings replaced

O-ring replaced

Per a suggestion from Sean Kirby, also clean off/out your evaporator. Great advice to get the most out of the system. Old cars, old systems. 

R134 A/C manifold for filling, extraction, and testing pressures. 
  1. All the old refrigerant needs to be removed. 
  2. Then flush the old oil and any contaminants out of the system. 
  3. Replace all the old o-rings with R134a compatible o-rings.  
  4. Vacuum the system, this step really helps with cooling. 
  5. Fill the system with recommended amounts of oil, and R134a
  6. R134a runs at higher pressure than R12
  7. R134a will generally not cool as well as R12 on a converted, non OEM, setup

Poor People Racing - R134a conversion

Proper R134a conversion

First step is determining the current gas in the system. If the system is R134a, or R12. Just because there are not R134a fittings on the system, does not mean one of the importers did not fill it to make it cold....then pull the fitting. I have seen no change of fittings, one fitting, and proper conversions. 

Next is to get the gas removed, and remove the evaporator assy. Drop glovebox, remove cross bar, remove 5 screws, and 3 electrical connectors at the top. Once removed, open the box. There are screws around the edge, and 2 clips holding the box together. clips are hidden under the foam insulation. once exposed, insert a flat tip screwdriver into the top of the clip, and pry up, DO NOT put the screwdriver through the side and try to pry, as the clip will actually exerrt more pressure and crack the housing. Seperate the 2 halves and clean out the evaporator core. You should replace the metering valve (240sx will work) Take care not to twist the wire for the suction temp sensor attached to the low pressure line. Using A/C flush, blow out all oil residue from the evap core. Assemble everything in reverse, using green o-rings (240sx kit will work) 

Condenser needs to be disconnected at front fitting, and at receiver drier, and flushed as well. Replace o-rings with green units.

Replace receiver drier, do not pull plugs/fitting caps off of drier until just prior to installation. Again, green o-rings. Take car not to twist low pressure switch wires from old unit, when removing, and when installing on new drier. 

Install fittings. 

Vacuum system for a minimum of 1 hour. This will help to pull any residual oils and moisture from the system. original oil in system was mineral oil, you need to replace with 4oz PAG oil. Factory Zexel DCW compressors require PAG46. Factory R12 charge was 950 grams +/- 50 grams. An R134a charge is 80% of the R12 charge. A good starting point is 1.2 lbs of R134a. 

Start car and monitor gauges. There are no exact pressures you will see on the system, and pressure is based on ambient temps. There are many charts online to follow based on this. 

Rule of thumb, you should have the system on, windows down halfway, on normal A/C and output at the center vents on high fan should be 30° lower than ambient temps. Adjust/fill as needed. 

I do not suggest using the cans you can get at the local parts store that come with the nozzle and you just plug into the low side fitting then pull a trigger. I also do not recommend using anything other than pure R134a. 

If you do not have access to the above, leave it to a shop to vacuum down and fill. Skipping these recommendations will result in poor performance, leaks, or compressor failure.

There are some other options, R12 substitute. Traveling to Mexico to get R12 on the black market. Living without A/C.  2 at 65 A/C - cooling.  Over time, we will add some of those other options here. Some cars don't have the auto amplifier A/C heater unit, but those are pretty rare. 

Cleaning interior air temperature sensor

This sensor is often left disconnected when someone works on the radio or triple meter in a car.  Sean from Poor People Racing, reminded us to check and clean the interior air temperature sensor, when cleaning the evaporator.  We just happened to have a center radio trim on the work bench, pulled the air sensor off, and cleaned it out with a small brush and some mass air flow sensor cleaner. 
Lots of crap inside the sensor assembly
Look at all that fuzz. 
Cleaned out with mass air flow sensor cleaner. 

Nissan R32 Skyline evaporator removal and refresh project *AMENDED

Buy USA Legal R32 Skylines at! for Nissan Skyline GT-R and GT-R parts.


Anthony said...

I tried ordering a expansion valve for my R32 GTR but it's discontinued. Would one from a S13 or 300ZX work? Thanks.

Unknown said...

1990 Nissan 240sx expansion valve will work

Unknown said...

How much oil and gas needs to go back into the system?