Trouble Shooting A/c In R33

[bistratoaie]

Yeah I believe it is located in the engine bay fuse box! Haven't tested it yet but I do have another spare sitting in a rolling shell at home so I can replace it if it's dead! Will let you know how I go and if that solves the problem, cheers

[Dose Pipe Sutututu]

On 27/09/2014 at 9:19 PM, Jaredo said:

I managed to fix my issue of rapid (instant on off, 1-2sec on to off, and long pauses between cycles) and random cycling of the AC even when the rest system checks out (right amount of gas, oil, dual pressure switch and climate control diag is ok),

There are a fair few mentions of the AC Thermo Amp being a possible culprit, I pulled mine apart to (they actually do come apart) to find a bulging capacitor. Replaced it and now it's back to awesome icy goodness and cycling normally.
You can get it out without degassing.
Your mileage may vary, this might not fix your issue, but it's worth a try if you have checked everything else.

Capacitor size: 33uf 25V (uf = microfards), get a 105deg rated one - 45cents at JayCar.
The temp rating of the stock part is 85deg.


1. If you pull the glove box out, then remove the panel behind it you can access the fan motor and evap core.
Directly in front of you, you should see a connector with 2 thick wires and a thin wire going into it (this is the FAN resistor).

If you look upwards from that to the top of the box you should see another connector and black small black box.

2. Remove the connector and then get a large headed flat screwdriver and pry it up from the right side towards the left-hand side of the car it should then come loose, if not stick your hand up there and pull it forward.
I already removed it by the time I took this photo and also didn't put it back. But it shows where its located.

Follow the cable up to the top of the evap box, use your sense of feel to find the little plastic holders from which you just slide the cable out of, do both so you can get some length.
Follow the cable some more and it'll go inside the box, use your fingers to remove some of the sealant if possible
Ref this picture to see how it's laid out.


3. Remove spring clip and 2 screws from the front of the unit, remove two large screws below the unit, there's one near the fan motor and one to the right of the sloping drain part.
3a. Remove the large screw to the left of where the thermo amp was.

4. Pull the bottom half box down a little, the seam should open up, you'll notice the evap core will also want to come down also.
Find something to keep the gap open unless you have strong hands.
It should look like this

5. Locate the temp probe on the right side of the evap core, the probe is on a clip that's just pushed into the fins
If you can get your hand in there, pull it out, else use a screwdriver try and lever it out. Careful you don't puncture the evap core


6. Once out, remove the clip so you can pull it out through the top.
Gradually pull the cable trough the top of the box till it comes out.


7. Once you have the control amp out crack it open, you'll probably have to break the outside case where the locking tabs are (locking tabs don't depress), use a really small or thin screwdriver.
Once that is done, slide the cover backwards a little.


8. Inspect the capacitor, the ends might be rounded instead of flat or it might look like it's buldging at one end and seeing as its going on 15+years it's probably at the end of it's life.
Desolder the old one, Solder the new one in.
Note the polarity, Negative is to the back of the board, positive at the front (there are also marks on the PCB). The capacitor will have it's negative leg clearly marked.

9. Test it before putting the system back together, leave the evap box open, and reconnect anything you disconnected. Leave the probe on the floor or something.
Run the car and AC, your AC should engage and should stay engaged.

If it worked then hurray! Put it back together.
if not, then the issue is somewhere else or the AC control amp is dead dead.

If you have a multimeter that can accept a temp probe (K Thermocouple) you'll be able to check what temps the AC control amp cycles between.
Mine cycles between 9.8 and 13deg C, that's plenty cold lol.

Ambient temp: 35.8deg C
AC compressor off at: 9.8deg C (Air vent temp, disengages around this temp)

AC compressor on at: 12-13deg C (Air vent temp, engages around this temp)

I really hope this helps others with the same issue, it's been a very tricky issue to resolve.

Bumping this thread, had the same stupid issue with my shit box, thanks @Jaredo for the instructions, no idea if you're still active here or not or have bought a M3 Competition and stopped playing with these shit boxes.

 

For the past year or so, been bypassing the HVAC to turn on the A/C compressor via the Haltech keypad as I couldn't find a replacement thermistor to test. Most newer Nissans use a 6 pin one, these shit boxes use a 3x one. I found one on Aliexpress that "might" work however didn't end up getting it and went down the route of trying to fix it.

So yeah, I removed the A/C Thermistor as per the above guide - it's a bit of a cnut of a job, however can be done with the dash still in. You can loosen the A/C evaporator enough to get a long set of pilers in to dislodge the probe from the core. I found it helpful to remove all 3x visible (larger) phillips head screw (with 10mm hex heads), then 2x smaller screws holding the housing together.

Ended up using a 47uF 25V capacitor from my random box of electronics shit, (OEM is 32uF 25V). Soldered it back on, slapped the cnut back together, reassembled everything and prayed to the Nissan gods that this would fix it.

And it did...

And the gods punished me by making the car leak coolant from somewhere between the rear of the head & gearbox. I suspect the hardlines from the NEO motor has rubbed with the Nitto head drain.

FFS.

And yes that small sheet of particle board, ended up falling on my car and scratching the front lip as I was inspecting the coolant leak.

Fk I hate this car.

[joshuaho96]

51 minutes ago, Dose Pipe Sutututu said:

Bumping this thread, had the same stupid issue with my shit box, thanks @Jaredo for the instructions, no idea if you're still active here or not or have bought a M3 Competition and stopped playing with these shit boxes.

 

For the past year or so, been bypassing the HVAC to turn on the A/C compressor via the Haltech keypad as I couldn't find a replacement thermistor to test. Most newer Nissans use a 6 pin one, these shit boxes use a 3x one. I found one on Aliexpress that "might" work however didn't end up getting it and went down the route of trying to fix it.

So yeah, I removed the A/C Thermistor as per the above guide - it's a bit of a cnut of a job, however can be done with the dash still in. You can loosen the A/C evaporator enough to get a long set of pilers in to dislodge the probe from the core. I found it helpful to remove all 3x visible (larger) phillips head screw (with 10mm hex heads), then 2x smaller screws holding the housing together.

Ended up using a 47uF 25V capacitor from my random box of electronics shit, (OEM is 32uF 25V). Soldered it back on, slapped the cnut back together, reassembled everything and prayed to the Nissan gods that this would fix it.

And it did...

And the gods punished me by making the car leak coolant from somewhere between the rear of the head & gearbox. I suspect the hardlines from the NEO motor has rubbed with the Nitto head drain.

FFS.

And yes that small sheet of particle board, ended up falling on my car and scratching the front lip as I was inspecting the coolant leak.

Fk I hate this car.

The ride truly never ends with these cars does it