Got the expansion valve on my air conditioning replaced today. I suspected the old one was stuck mostly closed, which was confirmed by gauge readings. The pipes up to the expansion valve were cold and sweating, but the a/c wasn't blowing very cold because the expansion valve wasn't letting enough refrigerant through.

This job ended up being a much bigger pain in the *** than I thought it would be. I'm going to get my rant out of the way now; you'd think that if someone is qualified to design an a/c system, or any part of a car for that matter, that they would be competent enough to realize that using plain steel bolts in aluminum is a bad ****ing idea. What ended up happening was the steel bolts that hold the expansion valve to the evaporator got stuck.

I got the one to come out by spraying it with kroil and working it in and out little by little (keeps the threads from getting torn up as much) until it finally came all the way out. I move onto the next one, and it's stuck worse than the other one was. Followed the same procedure, but the bolt sheared off about an inch and a half sticking out of the evaporator (could have been worse I suppose). I tried tightening two nuts together to wind it the rest of the way out with no luck. Then I tried welding a nut to the now stud that was sticking out which held fine, but sheared the bolt off again, this time an inch sticking out of the evaporator.

You can see the broken off bolt sticking out from the right.


At this point I figured I'm not getting the stud out without really ****ing something up, so I decided to try and work with what was sticking out. I used the old expansion valve to experiment with and see if I could drill the shoulder that the bolt's head catches on further down into the bod of the valve. Testing went well with the old valve, so I went ahead and drilled the hole further down in the new valve too.

The old valve is on the right and the new is on the left. You can see the right hole on the old valve was drilled further down and I was about to do the same with the new one. I couldn't find the end mills, so I just used a normal drill bit in the drill press.


Then I had to file a nut (the bolts are 1/4-20 thread by the way) down some so that it would fit in the hole and then cut a groove in it so that a flat screwdriver could be used to tighten it.

Here is the new valve installed. The modified side is on the right. I also replaced the original steel torx bolt in the left side with a stainless steel hex one and put anti-seize on it. Hopefully I'll never have to mess with the expansion valve again though.


After putting everything back together I pulled a vacuum on the system for an hour, let it sit under vacuum for half an hour to make sure everything was sealed properly, and then refilled the system.




It was 82° and humid when I got the system refilled, but even then the air coming out was right around 50° at idle and I'm fairly sure it will be well into the 40s when driving along.

 

after working in shops I think every engineer should have to repair they design, maybe then they'd figure out they are not as brilliant as they believe

 

Agreed

 

So I went for a short 10 minute drive earlier and the a/c got down to right above 40 degrees. There was even fog forming on the thermometer in the vent. So far so good.

 

That sucks, but thanks for posting it up. I might have tried drilling out the center of the bolt then use an extractor and finish with a re-thread. But it looks like she should hold the way you did it anyway.

 

def. great info thanks for the info I need to recharge mine but I may flush my system fiesrt as well beens I have the manafold set already It will be great to have the ice cold air come out of the dash for my comfort. thanks for the update. to your progress.

 

What size hex bolt this you buy and where did you get it? The same happened to a friends '99 on the right side and i am going to be attempting the repair over the holiday weekend. Good news (hopefully) is that his stud still spin back and the forward again to a certain point and then gets really tight.. My hope is i can get in there with a few sprays and work it full loose and just replace the stud.

 

I thought about trying to drill into the stud and tap threads for a smaller screw, but decided to try deepening the hole on the expansion valve first. Luckily I had the old one to experiment with and everything went well with it.


I don't know if flushing an a/c system is good for it or not. Make sure you vacuum the system down and only add the specified amount of refrigerant. It's on a sticker on the core support, it was 1.75lbs (28oz) for mine.


I just got the bolts from my grandpaps stockpile of bolts, so I have no idea where it came from, but if I had to guess it would be Westinghouse. From the base of the bolt's head to the end of the threads is 2". The bolt's head is 1/4", so the total length from the end of the threads to the top of the bolt is 2 1/4". The threads are 1/4"-20 and the hex bit it takes is 3/16". I made sure to load up the everything with anti seize too when I was putting stuff back together.




As far as getting the old ones out goes I soaked them in kroil and went back and forth with them, loosening a bit, then going back in some. It worked for the left one, but not the right one. Hopefully you'll have better luck with that than I did. I'm just glad that it didn't break off flush with the evaporator.

 

LOL noting tops Grand Paps stockpile of bolts.... When mine was still alive, i swear he had every bolt to every Dodge he had ever owned...

 

He still has engines from old mopars laying around. No big blocks sadly, otherwise one would be going in my Plymouth.