Expansion valve; how hard to change?

jrohland · 08-22-2009, 09:38 AM

It looks like the expansion valve in the AC on my T100 is stuck in the small appeture position (high pressure on the low side and the compressor cycles every few seconds). I have one ordered. How hard is it to get to the evaporator coil? Also, should I plan to replace the heater coil while I'm in there?

I will replace the receiver/dryer at the same time.

jrohland

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jrohland · 08-24-2009, 11:29 AM

I had the glovebox out on Saturday to undo some wiring mods. While there I took a look at getting to the evaporator and expansion valve. It looked about like most other vehicles. A pain in the back--literally but, only screws, cables, wires and pipes. Should not be too bad.

Funny thing is I am running the AC really low on refrigerant and it is working pretty well. If I try to juice it up, the low side pressure goes to high and the compressor cycles. With the charge very low, the pressure is kept low.

There should be plenty enough oil in the system to keep the compressor from getting damaged. The only real problem is there is not enough refrigerant mass to move large quantities of heat. Since the cab is pretty small, it is able to keep the front seats comfortable.

The expansion valve and receiver/dryer should be in soon. Once I get everything changed out, I'll let the vacume pump suck on the system for a few hours to try and boil out any remaining moisture from the oil and lines. As I'm sure you know, moisture is really bad for AC systems. It is really easy to rust the automatic adjusting appature in the expansion valve.

jrohland · 08-31-2009, 05:16 PM

I put the new expansion valve in today. It took a while because getting the old valve out without damaging the evaporator core was a problem. A new core is $200 so, I did not want to replace it.

Man, you don't want to know about the crap I found in the air box. It was disgusting. I expect the fan will be able to push a bunch more air with all that muck out of there.

Tomorrow I put in the new dryer. Should be able to wrap up the AC repair by tomorrow.

jrohland

jrohland · 09-01-2009, 05:17 AM

I pulled 29"Hg on the vacuum pump with the guages on. Left the gauges hooked up with the valves closed through the night. I check this AM before leaving for work. It is still holding 29". Of course holding a vacuum does not mean it won't leak under pressure but, at least I know there are no broken pipes.

After work I'll replace the dryer and charge it up. Be nice to get that one checked off the list.

jrohland

BamZipPow · 09-01-2009, 06:28 AM

What sort of refrigerant have you thought about putting in there? Would you consider some ES-12a?

Quote:

Enviro-Safe Refrigerants are hydrocarbon refrigerants that are ultra-efficient .
6 oz. of Enviro-Safe is equivalent to 18 oz. of R-12 or 16 oz. of R-134a. It is colder than either R-12 or 134a and has much larger molecules that are less likely to leak.

jrohland · 09-01-2009, 11:03 AM

It came from the factory with 134A so I going stay with that. I tried the hydrocarbon based refrigerant in my '82 Mercedes when I rebuild the AC on that one. It blew a seal in the compressor. I don't want to blame the juice since it was a very old car but, I think I'll stay with chlorofluorocarbon unless I am building a completly new system. In a new system I don't have to worry about contamination.

jrohland

jrohland · 09-02-2009, 04:52 AM

Changing the dryer is supposed to easy. I should know better. First the bracket bolt that clamps the dryer is rusted and snaps off. Great now I have to remove the bracket to use my extractor on the stud. What-da? I can't get to the bracket mounting bolts because the coolant recovery tank is in the way. To remove the tank I have to remove the left headlight. To remove that I have to remove the grill. To remove the grill I have to remove the bumper (see the photo).

OK I get all the stuff out of the way and remove the bracket. My extractor snaps off in the stud. Forget it, the bracket is about $20 I'll just get a new one.

I start removing the bolts holding the pipes on the top of the dryer. Snap, snap. They both break. OK I will just replace those bolts. Now what, the dryer pipes are corroded (aluminum so it is not technically rust) to the top of the dryer. Beat, beat, beat...with the plastic mallet. The only thing happening is damage to the pipes. Forget it, order new pipes. Now I'm up to about $140.

In the meantime, there is severe damage to the condensor coil. It looks like a tree branch jammed between the condensor and radiator damaging both. Amazing these things do not leak as much as they are smashed. OK add a new condensor to the parts list: ~$200. Do I really need AC? Yes, I do.

Radiator looks OK. The condensor took the bulk of the damage.

The saga continues...

jrohland · 09-15-2009, 06:27 AM

New condensor, three new pipes, new dryer, new bracket, new expansion valve, two cans of oil and 2.5 cans of R134 later...cold air, ahhh.

While I had the front end opened up (bumper and grille off) I pulled the radiator, flushed and cleaned it. You could not believe how much mud and debris there was hidden between those fins.

While I had the radiator out I changed all the drive belts. Since I have a supercharger and a 3rd party alternator, I had to find a custom sized belt. That took a few days.

It is finally all back together.

08-24-2009, 11:29 AM	#2 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	Maybe not that bad I had the glovebox out on Saturday to undo some wiring mods. While there I took a look at getting to the evaporator and expansion valve. It looked about like most other vehicles. A pain in the back--literally but, only screws, cables, wires and pipes. Should not be too bad. Funny thing is I am running the AC really low on refrigerant and it is working pretty well. If I try to juice it up, the low side pressure goes to high and the compressor cycles. With the charge very low, the pressure is kept low. There should be plenty enough oil in the system to keep the compressor from getting damaged. The only real problem is there is not enough refrigerant mass to move large quantities of heat. Since the cab is pretty small, it is able to keep the front seats comfortable. The expansion valve and receiver/dryer should be in soon. Once I get everything changed out, I'll let the vacume pump suck on the system for a few hours to try and boil out any remaining moisture from the oil and lines. As I'm sure you know, moisture is really bad for AC systems. It is really easy to rust the automatic adjusting appature in the expansion valve.

08-31-2009, 05:16 PM	#3 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	It's in there I put the new expansion valve in today. It took a while because getting the old valve out without damaging the evaporator core was a problem. A new core is $200 so, I did not want to replace it. Man, you don't want to know about the crap I found in the air box. It was disgusting. I expect the fan will be able to push a bunch more air with all that muck out of there. Tomorrow I put in the new dryer. Should be able to wrap up the AC repair by tomorrow. jrohland

09-01-2009, 05:17 AM	#4 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	Looking good...so far I pulled 29"Hg on the vacuum pump with the guages on. Left the gauges hooked up with the valves closed through the night. I check this AM before leaving for work. It is still holding 29". Of course holding a vacuum does not mean it won't leak under pressure but, at least I know there are no broken pipes. After work I'll replace the dryer and charge it up. Be nice to get that one checked off the list. jrohland

09-01-2009, 11:03 AM	#6 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	I'm going with R134A It came from the factory with 134A so I going stay with that. I tried the hydrocarbon based refrigerant in my '82 Mercedes when I rebuild the AC on that one. It blew a seal in the compressor. I don't want to blame the juice since it was a very old car but, I think I'll stay with chlorofluorocarbon unless I am building a completly new system. In a new system I don't have to worry about contamination. jrohland

09-02-2009, 04:52 AM	#7 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	Nightmare on my street Changing the dryer is supposed to easy. I should know better. First the bracket bolt that clamps the dryer is rusted and snaps off. Great now I have to remove the bracket to use my extractor on the stud. What-da? I can't get to the bracket mounting bolts because the coolant recovery tank is in the way. To remove the tank I have to remove the left headlight. To remove that I have to remove the grill. To remove the grill I have to remove the bumper (see the photo). OK I get all the stuff out of the way and remove the bracket. My extractor snaps off in the stud. Forget it, the bracket is about $20 I'll just get a new one. I start removing the bolts holding the pipes on the top of the dryer. Snap, snap. They both break. OK I will just replace those bolts. Now what, the dryer pipes are corroded (aluminum so it is not technically rust) to the top of the dryer. Beat, beat, beat...with the plastic mallet. The only thing happening is damage to the pipes. Forget it, order new pipes. Now I'm up to about $140. In the meantime, there is severe damage to the condensor coil. It looks like a tree branch jammed between the condensor and radiator damaging both. Amazing these things do not leak as much as they are smashed. OK add a new condensor to the parts list: ~$200. Do I really need AC? Yes, I do. Radiator looks OK. The condensor took the bulk of the damage. The saga continues...

09-15-2009, 06:27 AM	#8 (permalink)
jrohland Registered User Join Date: Aug 2009 Location: Northern Virginia, USA Posts: 108	How cool is that? New condensor, three new pipes, new dryer, new bracket, new expansion valve, two cans of oil and 2.5 cans of R134 later...cold air, ahhh. While I had the front end opened up (bumper and grille off) I pulled the radiator, flushed and cleaned it. You could not believe how much mud and debris there was hidden between those fins. While I had the radiator out I changed all the drive belts. Since I have a supercharger and a 3rd party alternator, I had to find a custom sized belt. That took a few days. It is finally all back together.

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