AC leak test results...possible new evaporator needed?
#31
Rennlist
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Basic Site Sponsor
1. Evaporators generally fail from a bad freeze switch...or some rocket scientist disconnecting the switch to get colder air. The evaporator freezes and the ice cracks the tubes.
2. Every leak detector made will go off when air is being pushed into it. Useless test....they should know this....so that either points to a HUGE leak or a con. Makes one wonder if the leak at the fill valve was intentional to make you think the evaporator leaks....
3. Freon is heavier than air. Check for leaks at the drain, with system charged system hot (highest pressure possible on the "low side" (evaporator is on the low side) and fan not running. Vehicle off works best.
4. The best evaporator "test": Pull back the boot between blower motor and evaporator housing (under front cowl). You can see the entire top side of the evaporator. If there is a leak, there will be oil with dirt stuck in the dirt present. If there is dye in the system, you should've able to see it with the oil and dirt.
5. If there is no oil present, you will probably be stunned at the amount of dirt blocking the evaporator....wondering how any air could pass through the evaporator. Cleaning can be challenging,,,,that's a different topic.
6. If the evaporator is leaking, that shop is going to be really sorry they quoted such a low price....they have obviously never done this job....or have a very low hourly labor rate.
Which leads to #7:
7. Ask them to put all the pieces they have left over and have no clue where they go into a baggy in the glovebox. This makes locating those pieces, when someone who has seen more than one of these cars, much easier.
2. Every leak detector made will go off when air is being pushed into it. Useless test....they should know this....so that either points to a HUGE leak or a con. Makes one wonder if the leak at the fill valve was intentional to make you think the evaporator leaks....
3. Freon is heavier than air. Check for leaks at the drain, with system charged system hot (highest pressure possible on the "low side" (evaporator is on the low side) and fan not running. Vehicle off works best.
4. The best evaporator "test": Pull back the boot between blower motor and evaporator housing (under front cowl). You can see the entire top side of the evaporator. If there is a leak, there will be oil with dirt stuck in the dirt present. If there is dye in the system, you should've able to see it with the oil and dirt.
5. If there is no oil present, you will probably be stunned at the amount of dirt blocking the evaporator....wondering how any air could pass through the evaporator. Cleaning can be challenging,,,,that's a different topic.
6. If the evaporator is leaking, that shop is going to be really sorry they quoted such a low price....they have obviously never done this job....or have a very low hourly labor rate.
Which leads to #7:
7. Ask them to put all the pieces they have left over and have no clue where they go into a baggy in the glovebox. This makes locating those pieces, when someone who has seen more than one of these cars, much easier.
#32
Rennlist Member
Thread Starter
Good info, Greg, I will check that stuff.
They claim to have worked on a few of these cars "back in the day." In general, the place is cheap enough I can't see it being a con...but I'll admit I was pretty surprised to find such an obviously loose fill valve. Maybe I should make them honor their evaporator replacement estimate as punishment? Honestly though, I have other things I need to do under that dash...including replacing or recovering the dash itself...I'm just not ready to do it all yet. I'm leery of having anyone I don't know to be a 928 expert poking around in there. Ha ha the baggy thing is a good idea actually...
They claim to have worked on a few of these cars "back in the day." In general, the place is cheap enough I can't see it being a con...but I'll admit I was pretty surprised to find such an obviously loose fill valve. Maybe I should make them honor their evaporator replacement estimate as punishment? Honestly though, I have other things I need to do under that dash...including replacing or recovering the dash itself...I'm just not ready to do it all yet. I'm leery of having anyone I don't know to be a 928 expert poking around in there. Ha ha the baggy thing is a good idea actually...
#33
Rennlist Member
When my 300E's evaporator gave it up the evidence was a freon puddle under the car. I would see if the freon made it to the floor under you car near the drain.
#34
Archive Gatekeeper
Rennlist Member
Rennlist Member
Freon puddle? You mean oil/dye puddle?
#35
Rennlist Member
#36
Rennlist Member
What was the temperature when your evap let go?
Unless something has changed that I am not aware of R12/R134 boil at around -26C.
On the positive side if it was that cold you do not need the a/c!
Rgds
Fred
#37
Rennlist Member
Summer - a green puddle was on the shop floor.
#38
Rennlist Member
Thread Starter
Interesting...I certainly have seen no indication of dye on my floor. I suppose a smaller leak might just spray out on the surrounding area, but given all the condensation that has to drain, you'd think some of the dye would get in there.
I had some water dripping on my leg during cornering the other day...I'd hate to get green dye on my new carpet...but it would certainly show up there lol...
I had some water dripping on my leg during cornering the other day...I'd hate to get green dye on my new carpet...but it would certainly show up there lol...
#40
Rennlist Member
You can get a leak detector kit at your local auto parts store. Check the carpet where you got dripped on.
#41
Rennlist Member
Thread Starter
I will definitely take a look at the drain itself. I haven't had any water on the carpet since that previous time....I'm thinking the drain hadn't been used for a while, and suddenly with water flowing through it it backed up a bit and then maybe cleared itself out.
Any thoughts on tightening that elbow fill valve? Is cranking it down REALLY tight a bad idea? I don't like the idea that I have to loosen it to attach a hose right now...
Any thoughts on tightening that elbow fill valve? Is cranking it down REALLY tight a bad idea? I don't like the idea that I have to loosen it to attach a hose right now...
#42
AC evaporator Leak test
To test a leak evaporator using a smoke machine:
Remove the expansion valve plug one side of the evaporator (low side or High side) with a rubber plug
insert the smoke machine line to the other side of the unplugged evaporator side. Run the smoke machine for
about a minute and then monitor the vents inside the car. If smoke is coming out from the vents then the evaporator is leaking.
Remove the expansion valve plug one side of the evaporator (low side or High side) with a rubber plug
insert the smoke machine line to the other side of the unplugged evaporator side. Run the smoke machine for
about a minute and then monitor the vents inside the car. If smoke is coming out from the vents then the evaporator is leaking.