I have the rear A/C evaporator leaking. I put the gages on on and it would not hold pressure very long. While it had pressure it made 39 degree F air but quickly warmed up over a 5 minute time period. I sniffed around and got and got a full scale reading near the rear evap unit. The UV light showed all kinds of green spots in multiple places on the ribs so it definitely needs to come out.

My question is........ Should I change the rear heater core while I have that case apart? I have never had a rear heater core failure on any of my rovers and just thinking a preventative measures.

I suppose I could split the difference and flush it out and then make the decision after I see what it looks like.

What are your thoughts?

Jeff

 

Yeah i would flush first and see how it goes.

 

I dont think the rear cores are known for leaking. But I would probably remove it and do a really good proper flush to see what all comes out. New ones are not super expensive tho. Kind supersede your rear AC evap is leaking, again never heard of that happening.


edit: FYI, there is a valve that opens and closes refrigerant to the rear unit. There was also one intended for the rear heater core but as far as I know it was never put in at factory, still in service manual tho.

 

Since the evaporator has not arrived, I am delaying any repairs. I did however, pull it out and clean the left rear wheel well to remove as much mud and muck as possible in an effort avoid getting any of it in the A/C lines.
I knew there was a control valve in the back but it just shuts off the high pressure side. IF there is a leak in the evaporator, it will continue to leak regardless of the valve position as the low side is still connected (Ithink).

I looked at a way to just remove the front of the case and unbolt everything but.....NOOOOOO! I do not think there is enough room to pull the front off and then disconnect the lines from the back of the case. The unit is too far back into the fender well. Plus I am not sure what will fall out once the front case is removed. (I will let you know which I do it. Worse case is I pull the front off and then have to remove the whole thing.

There a virtual desert of information on the internet or youtube on repairing this thing, so I am stuck following the service manual which, as usual, requires about 15 more step than it should. Such as remove the spare tire, remove three exhaust hangers, move the exhaust over and remove exhaust shield etc. etc.

I can see it from underneath, so I think I can just bend the shield back and reach up there to get to the connections.

Wish me luck.

 

So I have completed the rear Evap Coil replacement. Here are some thoughts for those willing to tackle this problem.

The manual says remove the spare tire: it was nice as it allowed the exhaust to move more and give you just a little bit more room..
Remove the rear and center exhaust hangers: absolute necessity. The wiggle room needed to remove the heat shield and then reach the coolant line clamps and A/C connectors is a plus.
The coolant lines had a strap that needed to be removed in order to get the clamps off of the hoses slid back.
The A/C lines connect right at the floor level and it was hard for me to reach and seemed to be rather hard to disconnect (typical of A/C O-ring connections) the install was the most difficult part because the lines did not seem to line up once the unit was mounted back in the car.

I disconnected everything as described in the manual and set the box on the workbench. The disassembly was straight forward. I disconnected all of the plugs to all of the items and moved the wire harness out of the way as most of the hold down clips were on the front of the box. Although not required, I removed the fan just to make the front case a few pounds lighter. I removed the Evap Coil with no issues and noted the 3 lbs of dog hair it had collected. Once out of the box I put the U/V light on iy and I had little green spots on nearly half of the coil. I left the heater core in place and flushed it out both forward and backwards. I do not know which was input or which was output, I just flushed both way to be sure. It was easy to do and it was clean and flowed well.

Reassembly of the box is straight forward, just make sure the blend door that sits in front of the heater core is located in the slots on the top of the core and slides into the indentation for it on the front of the box so it will move freely once installed. I would recommend to loosely mount the box until the heater hoses and A/C lines are reconnected.

I hooked up the gauges and vacuum pump and let it run for about 30 minutes.
The underhood placard showed 2 lbs of R134a =/- 1 oz. the parts store sells cans in 12 oz sizes so I got three cans off the self and started to fill the system. I put one can that had oil included in before starting the car. I then hooked up the second can and ran it until the pressure equalized. At this point I started the car, set the A/C on both front and back to max cold, and let the second can get emptied. I used an R134a chart to determine the pressure for the current temp and stopped at 47 psi on the low pressure side. I let the car run for a few minutes and got 59 degrees F in the vents. Not great, but I will take it.

I got out the sniffer and it went crazy at the connection that I just reconnected and thought that I still had a leak. I shut the car off, got out the air suspension test tool ( bottle of soapy water) and cleaned the connections as best I could. as it was in the late afternoon, I let the car sit overnight and sniffed for leaks again. This time it was quite, so I reassembled everything, pulled out it of the shop and gave the keys to my wife and told her to let me know if it gets hot again.

Since the forum seemed void of this topic, I thought I would do a little write up in hopes of helping someone else with this problem.

Jeff

 

Nice work! I am sure some day I will have to tackle it.

Note on the oil, generally you dont add any. R134a, unlike the old R12, does not carry oil away in a leak nearly as much and pulling vacuum will not remove oil. Too much oil will stress the compressor and greatly reduce performance. But you do need a bit much. Usually the oil on these systems stays pretty much where it should, at the compressor itself. This is also why when buying compressors, they come with the required oil type and quality already inside the compressor. If the oil quantity is not known in a system, its best to remove the compressor and drain it. You can measure what came out. Then add almost all the oil specified, I say almost all because some oil will make its way around the system. Or if the amount that came out of the compressor was close to spec, add that back in.

 

Well truth be told...... The first can said something like "Ice Contact Formula to help lubricate the system" or some such. I did not specifically add any oil.

Jeff