AC evaporator core
 

I switched my fd from r12 to 134 and of course now its leaking like hell from the center vents. The garage said I had a leak in my evaporator core. Somehow I doubt that. I figure the leak must be from orings since the core didnt leak before.

I have seen various threads saying you must remove the dash to get at the core. this thread says you dont.

https://www.rx7club.com/forum/showth...53#post4222253

Do you or dont you need to remove the dash to replace the core? He just removes the glove box and air bag. I dont have an air bag :(

Secondly. If it is just the orings... where are these orings? Are they the orings around the expansion valve?

If the o-rings were leaking, I have a hard time picturing how they would then leak into the ducting and come out the center vent. They would leak out into the space under the dash. The core is the only place I know of where the refrigerant could leak into the ducting, but I don't know enough to say it for absolute certain.

The o-rings exist anywhere that A/C components are connected. There are many of them, and should be replaced anytime a component is disconnected.

Yes, evap cores do die sometimes. Maybe by improper handling during the conversion process, so you may have a case with whoever converted it. They should do a hard vacuum test to detect for leaks before filling, which should have prevented this problem.

Dave

thanks for the input. I suppose you are right. Although he didnt test under the dash, it was off the scale on the sniffer coming from the center vents. Supposedly he did a leak down test in the process of sucking out the remaining r12. It didnt leak for about 4 days. Then, no ac. He refilled it with 134 and it was empty within a day. Thats why I was kinda leaning towards orings. But I hadnt thought about how it would route through the center vents. Damn, since I have a 93 I guess im looking at about $900 in repair bills again and thats assuming you dont have to remove the dash! This thing is a never ending money hog.

Hang on mate, i am also qualified to work on A/C systems....
The way it works is that as refill station, you have to pressure and vacuum test the system... Without pointing fingers, but to give you a clue, system pressures fluctuate between 1.8 bar in the low pressure side(expansion valve onwards) and 18 bar high pressure side(pump, condensor towards expansion valve)

Static system pressure(high and low, since they working as communicating barrels) is about 5 bar at 20 degrees Centigrade.

K, now the pressure test........ most stations purge the complete system, high and low side to 15 bar!!!! Whilst the low pressure side of the system is not made to handle this... If they fooked up with the pressure test and for example let it slip to 20 bar they busted your evaporator.
Next they have to do the vacuumtest, your system probably failed this test, or it has not been done, since they noticed that the pressure test was a "blow out".

They just filled the system and are saying that it is leaking like hell all of a sudden, O-rings are absolutely not to blame, they are perfectly capable of handling the switch from R12 to R134. Done loads of systems and had no problems.

Busted evaporator, just after refill....... more than likely a fault at the service station that did the test.

any updates? I have the same symptoms, dealer said expansion valve is leaking, ac shop said evaporator is leaking... ???

A couple of things:

1) As I have written in other threads on R134, it is problematic. R134 is a much, much smaller molecule than R12 (or plain air); consequently, it will find leaks that you may not know you had. There are also longer term affects that result due to materials and oil compatibility problems. I doubt that this problem was caused by the conversion process. Where possible, I recommend converting to a hydrocarbon refrigerant such as HC-12 or ES-12 as it has numerous performance benifits and it will not leak out as readily (as 134).

2) You can, in fact (I have done it), remove and replace the evaporator by simply removing the glove box. I takes a little work to get the fittings off but it is manageable. I was able to pull the evaporator this way, replace the thermoswitch and reinstall in an afternoon.

3) There are two different types of evaporators used on the FD. Be sure you know which one you need when sourcing a replacement.