AC Expansion Valve Repair and Setting

[sblake01]

ah i see. no i agree with you, id rather have r12 in it then 134a. i had a bmw with r12 and that thing was a ice box. ive been in brand new cars in 110 degree weather and it was never as cold.

My 2005 GTO and my wife's 2006 Chevy HHR will both freeze you out. They're both R134a systems. My 1990 Ranger will also freeze you out and it's a R12 system so I guess that really depends on the vehicle.

in that case i hope mine isnt r134a.. and since you said there would be a stamp i assume it wasnt, or the dude vacuumed it out and didnt put r12 back in. if that is the case could there be any damage to the system if not converted properly? or can i just flush it out and put r12 in it?

Problems can occur in R134a conversions when they're not completely cleaned out during the process and some reamaining mineral oil left from the R12 charge mixes with the PAG oil used with the R134a. As Andrew said in post #5, it will gel (I hope that's not what you were describing in post #8). Even if I was just going to flush out, vacuum and recharge the your system with R12, I would, at very least, replace the receiver/drier also.

[ZCurves]

ah i see. i havent seen a tag anywhere so i assume it wasnt. and i assume there was some r134a because thats what the guy said was in it when i bought it.. right now the whole system doesnt even kick on. no fans no nothing so i got to fix that first.

would you know how much it would cost to replace some of the parts like the expansion valve to newer 134a parts and do the conversion?

Here is what I spent (to the best of my knowledge) to do a complete and proper conversion to a R134 system.

Condenser: $100

Evaporator: $60

Dryer: $25

Pressure Switch: $5

Expansion Valve: $20

Custom Make-up of High/Low Lines (R134): $80

NOS Compressor (Nissan 810): $100

Refrigerant & Oil: $25

So we're looking at ~$450

I also added an electric fan to the Condenser because R134 creates more Head Pressure. The fan is run off a relay wired to the AC, so it runs only when the compressor is on.

The Custom Hose Make-up was necessary not so much for R134 refrig but because I wanted to replace the aged hoses and allow for the use of the compressor from the 810. I did use Goodyear Barrier hose specific for R134. The Custom Hose Make-up has some tricks to it which I can explain further to anyone interested - just ask.

I can also help anyone reading this to find the same parts, if needed.

[sam280z]

Andrew,

Where did you source the evaporator and expansion valve?

Sam

[sblake01]

Sam, read through this thread on ZCar.com. Note the posts by ZSPEED77. There are some pictures attached to post #10.

http://www.zcar.com/forums/869824/evap-expansion-valve

Edited August 18, 2010 by sblake01

[zeefan]

I've never been a proponent of putting R134a in a system that was designed for R12. The R134a molecule is smaller than the R12 molecule coupled with the fact that R134a requires higher pressure to adequately cool which would tend to make the system more susceptible to leaks than a system purpose built for R134a. For that reason I've always used either R12 or a R12 substitute like Johnsen's Freeze 12 when charging an R12 system. I know R12 costs a fortune these days but I lucked into a jug of it at a yard sale last year that had about 23 lbs. left in the cylinder and the lady sold it to me for $25! Systems become problematic for different reasons so I would only be guessing at the repair cost without actually doing an inspection.

I tend to agree for the most part. Depending on your jurisdiction, you may be legally entitled to other (R-134a) alternatives. I am aware that the US EPA has been a 'PITA' as far as accepting 'other' refrigerants into the marketplace. In Canada, the use of HC-12 products is widely accepted and totally legal. Anyone who is even remotely familiar with the pros and cons of R-l34a and HC blends will understand why the former is not a wise choice. But, having said this, the automotive industry and manufacturers such as Dupont have elected to go in one direction. The logic escapes me. However, if you do some research, depending on the State you reside, there may indeed be legal and safer and more efficient (R-134a) alternatives already available.

I recall that some jurisdictions made it illegal to use (HC) refrigerants inside any automotive system that was originally designed and used for R-12 (freon). Okay. But, the way around this was to set up a conversion for R-134a (and then install the HC product).

Finally, I am NOT advocating HC products (such as duracool.com). I am simply suggesting that the misinformed enthusiasts partake in a little basic research before they (blindly) follow the advice of their local mechanic/tech/dealership. thanks.

[sblake01]

I'm not looking for your agreement or approval, thank you. I am a licesned HVAC/MVAC tech. Not sure if I mentioned that in this thread or not. I've done the research and I prefer not to use HC refrigerants. I've tested REDTEK12, an HC based refrigerant, and found that it cools well but Freeze 12, which is non flamable, cools a little better. I have enough R12 to not have to use either. I won't get into a discussion of the pros and cons of HC based or any other refrigerant other that stating my preference and I'd suggest to you that you shouldn't offer 'work arounds'. Besides, it really doesn't have anything to do with the subject matter of this thread which is "AC Expansion Valve Repair and Setting". My response was simply to shade 133's 'sidebar' question.

Edited August 18, 2010 by sblake01

[zeefan]

The only thing I am advocating is to not convert to R-134a. When I joined Allpar several years ago there were many opinionated and misinformed MVAC techs who pretty much thought that the sky would fall if they used an HC refrigerant. It took about a year for them to do the research and realize afterall that the 'flammability' issue was not at all an issue but more of a paranoia. :paranoid: Now these licenced techs have learned to think for themselves and they are concientiously and intelligently doing conversions the logical way. I was (mistakenly?) under the impression that Freon was technically ILLEGAL to use in North America but maybe only in Canada. :stupid: Isn't it ironic to not advocate 'retro-fits' to R-134a / HC but to go ahead and use the 'banned' R-12?

And, on the topic of the expansion valve, I know how important it is to have a 'clean' one and when the mineral oil becomes contaminated there will be probable high-pressure issues. Thanks and this is my last word on the subject. :kiss:

[sam280z]

sblake01, Thanks for the link. I had seen that thread, but it doesn't say where he got the evaporator.

I read the evaporator R&R instructions in the FSM I saw that it supposedly comes out w/o removing the dash so I am now considering this option.

I tested all of my expansion valves and my friend's new one by blowing low pressure compressed air through them and spraying the sensing bulb with the liquid from an electronics duster can of "air". The new valve and the one I had played with the setting screw shut off the flow of compressed air after a few seconds of being frozen. The other two did not, so I assume they are broken (lost the charge in the sensing bulb). I installed the one that seemed to work after trying to get the screw in about the same place as the others. It cools, but not nearly as much as it should. When I get the highside pressure to where it is supposed to be, the lowside pressure is a little low. I think I have the super heat set such that the valve closes too soon limiting the amount of R12 in the evaporator and limiting the cooling.

My thinking is that if the these EV's are that fragile I should find an alternative.

Another option I'm considering (if I can't find a supplier of the aftermarket evaporator) is making an adapter that fits where the stock EV goes that would allow the use of an aftermarket EV. It would basically be a gutted and opened up EV that would attach to a functional EV. the biggest issue with this is the 90deg bend required on the inlet hose.

[sblake01]

This quote is from that thread. I just couldn't find the other thread that is referred to in the quoute. You might try contacting z_again or ZSPEED77 from that site:

I found the post about AMC Imports in Texas that has the evaportaor/expansion valve set up for $225. Likely the same one at Kragens for $291. Plan on buying it and putting it in.

Edited August 18, 2010 by sblake01

[sblake01]

Isn't it ironic to not advocate 'retro-fits' to R-134a / HC but to go ahead and use the 'banned' R-12?

No irony, really. It is completely legal in the US, under Section 609 of the Clean Air Act, for a certified MVAC tech, to purchase and use the remaining supply of R12. You can buy it 'new' if you're certified and wish to pay upwards of $700 for a 30 lb. jug. And that is my last word on the sidetrack.

[ZCurves]

Andrew,

Where did you source the evaporator and expansion valve?

Sam

Sam,

I am not sure what city that you live in, but you should shop around because I have found that prices are all over the place. I am still looking for of my old receipts to help you out.

One good source is www.1800radiator.com. Your local parts house is another.

I purchased the Evaporator locally, but I found one here:

Part #249-293 $193.04 (http://aircomp.autoitech.com/) seems a little high.

Dryer:

Part #60-30571 $40 (http://www.discountacparts.com/Nissan-280Z-A_C_Accumulator_Drier-60~30571.html)

Condenser:

Part #SILLAC8060 $78.57 (http://www.autopartsdeal.com/catalog/?N=1684+11380+4294962110+9171)

I would suggest that you purchase the Evaporator and Expansion Valve from the same place - this way you can make sure that there is a proper fit. Since the OEM Evaporator Cores are no longer available, the ones that you will encounter will have the flared Expansion Valve fitting (remember to lube up fittings with the appropriate Refrig Oil before assembly!!).

DO NOT get frustrated looking for parts, we're talking about AC parts NOT Rocket Engines. MANY MANY cars used the same components and the parts ARE available. If something is not immediately available, just ask the supplier -you will be amazed...

You could get creative and alter the short copper high pressure line under the dash, changing it to contain a Orifice Tube at the point where it passes through the firewall. Any AC shop that does custom hoses and lines could make up one where the line is extended to to Evaporator Core eliminating the Expansion Valve. It is important to have the Orifice Tube located at the firewall so that it can be replaced(if needed) in the future.

[sblake01]

Had I kept my 280Z, I had planned to a complete conversion to include the use an orifice tube instead of an expansion valve. I would have used R134a since the components would have been up to the task. I ahve all the equipment to do that. I just never got around to it since the system that was in it worked so well.