AC compressor valve replacement

Hi all,

After doing all my seals etc and changing over to 134a gas as R12 is now banned where I live, I know have a leaking valve on the compressor. Does anyone know where to get one of these or the specifications?

I've circled it in red on the photo below.

Thanks,
Craig.

 

the promised photo is missing ;(

 

Hi Joe, thanks for point it out. I seem to have having posting photos these days. I can see them on the posts. Im using fchat for hosting them so no idea why this keeps happening. I'll try and host somewhere else and change the photo.

 

Hopefully this image can be seen.

 

still nothing to see
only

 

Craig, no pictures here also, but are you talking about the fittings on the compressor where you attach the pressure gauges? The fittings each have a schrader valve core that screw into them. If you are lucky one core might just need a little tightening. If you have the little tool to install and remove the schrader core, try to snug them first so you don't have to blow the charge. They do sell replacement cores, but they may come inside a fitting that you will not need. Try a local refrigeration supply house. For example, you may see a very inexpensive five-pack of "line service valves" which are 1/4 inch SAE male flare, with a stainless steel valve core suitable for all refrigerants. I believe that means the little seal type on the core is blue for all refrigerants. Not sure, but I have seen red which may be for air or maybe black? Just tell the supply house what you are trying to do. EDoug

 

No pics for me either, but as EDoug says, a drop of PAG and tightening on the valve to get it to reseat can sometimes help. If you need to replace the Schrader valve without evacuating and refilling, Mastercool makes a cool product

https://www.amazon.com/gp/product/B000KITSMI/

 

link is not working

 

Just google for this:
Mastercool 81490 R134a Valve Core Remover & Installer

 

how should I know this what to have a look for when the link is not working and so I not see anything?
thank you for the right words to look for

 

Thanks all. It is indeed the schrader valve. Ill try and tighten it this week see if it helps. If not Ill find a replacement as I've recovered the gas for now as I didn't want it leaking everywhere.

On a side note I messaged the Fchat help about the photos as it seems to be on all my threads but no response in 5 days. Anyone know who I can reach out to for help with this issue?

 

you may contact the founder of ferrarichat - Rob Lay

 

So I have the schrader valve now fixed and have just started the car to fill it. However the compressor clutch is not engaging when its being filled. Fan is blowing full, temperature is at minimum. Resistance on the adjustment knob is correct and swings.

I've jumped the two wires on the connector at the pressure sensor on the drier. I've also checked as per the workshop manual the resistance between the pins on the 6 wire connector going to the HVAC controller (located behind the fuse panel) and the Ohms are all pretty much what they should be for each temp sensor - Heater Sensor, Cooler Sensor and Passenger cabin sensor.

I'm a bit lost as I cannot see anything else in the workshop manual that descibes how to test the compressor clutch.

 

To add to this I have also now checked the following which I found on another post from @Steve Magnusson


There is a relay on the AC unit that could be causing your trouble, but you can confirm/deny if it is working properly or not by making some voltage measurements at the AC ECU connectors (the AC ECU is mounted behind the fuse-relay panel and has a 4-pin and 6-pin connector). With everything still plugged in these measurements are made on the 4-pin connector:

1. Start with key "on", AC "stop" button pressed -- measure the voltage on pin III (the three M brown wires) relative to ground (the battery "-" post) -- should be +12V. CHECKED AND OK

2. Press any of the three AC buttons -- measure the voltage on pin I (the single VB green/white wire) relative to ground -- should be +12V if the relay located on the AC unit is OK/working. If not, then you would maybe have to replace/check this relay on the AC unit (but it could be a problem with the push button switch assembly too). CHECKED AND OK

3. If you pass 1 and 2, set the controls to request cooling and measure the voltage on pin II (the two CN orange/black wires) -- should be +12V if the AC ECU "thinks" it needs to turn on the AC compressor for cooling. +12V NOT FOUND

 

To update the above Ive tested again the sensors as pin 1 to 4 kept fluctuating.

Ambient temp is 38 DegC

Pin 1-2 should read 5777 ohms and I get 5850
Pin 1-3 should read 1592 ohms and I get 1580
Pin 1-4 should read 5565 ohms and now I have no reading.
Pin 1-5 should read 0 to 10000 ohms and I get 3 to 10530
Pin 1-6 should read 10000 ohms I get 10480

 

you may test with an additional wire direct from battery plus ( take this plus from the starter ) and connect this to the magnetic clutch ( disconnect the orignal wire ) when the engine is not running. so you can hear a "click" if the clutch is ok.

 

Definitely has to be fixed, but, by "no reading", do you mean infinite Ohms or zero Ohms? If infinite Ohms, maybe the cabin interior temp sensor has just been unplugged, or you need a new one (61079100) -- anyone been digging around on the LH lower side of the dash?

PS I don't like the extra space in the 1-4 data on page H30. Might be a missing comma, but that would imply a crazy resistance accuracy of hundredths of an Ohm so probably just an unwanted space.

 

Hi Steve,

I've removed the sensors from the dash. Its actually broken hence there is no reading. No idea how it could have been when the new carpets were installed last year.

I've not been able to find a source for it yet. Not even on ebay.

 

Thanks Joe. Checked and the clutch does engage when directly connected.

 

Craig, just wondering if you put in new schrader cores or just snugged them up?

To your new issue, maybe something else to try here. No doubt Steve M is as good as they come on this electric stuff. But are you refilling the 134a from small cans, or are you filling from a 30lb tank? Many times when I am using small R12 cans it seems like I cannot completely empty each can into the system. So I take a deep pan with the hottest water I can put in it and place the small freon can into the hot water and let it heat up. The heat will drive the remaining freon gas into the system and empty the can. If you drive enough freon into the system sans clutch to get above the low pressure compressor cutout setpoint, maybe your compressor will be enabled. Just a thought. EDoug

 

I put new ones in. One of the old ones had ceased in place so the entire fitment had to be removed and machined.

For the 134a I'm using a 30lb tank.

The issue would appear to be the cabin air temperature sensor as its snapped.

 

Hi all. I've ordered an Adafruit 10k B3950 NTC Thermistor Temperature Sensor which has almost identical resistance numbers across the temperature range. I'll solder it onto the original pins on the old unit and see if they fixes the issue.

There is no availability for these anywhere. I've had feedback from a few of the good Ferrari parts suppliers and even had nothing turn up on Ebay.

I'll report back if it solves the issue or not once I've received it next week.

 

It will be interesting to see if the Adafruit sensor holds up to the harsh automotive environment over the long term. Thanks for evaluating the response curve. Please consider adding that to the cross reference thread.

 

Just to confirm it was 100% the interior cabin ambient temperature sensor that was faulty. The new Adafruit 10k B3950 NTC Thermistor Temperature Sensor was installed into the original location and all works perfect again. At an ambient temp of 34 Deg C it should be 6635 ohms and I'm getting 6708.