UCFAlumni2000

Symptoms: I have a 2004 SE, AC hoses replaced in 2008, air worked perfectly since until 2 weeks ago. Now when AC is turned on there is a 5 second moderately loud sound coming from the Cooling Unit Area behind the instrument panel. The sound comes and goes every 10 min or so. It sounds like when you open the valve on a scuba tank or propane tank and you hear the pressurized gas flowing from a high pressure to a low pressure, like a slow moving rush of air. Since this sound started the air coming out of the vents varies between room temp to slightly cool but not cold. I have not gone to the shop yet to have them run diagnostics and check the pressures but my guess is that the expansion valve (TXV) is sticking or clogged or barely opening which is what causes the noise.

The manual on page ATC-125 says to replace the expansion valve as follows: a) discharge the refrigerant, b) disconnect the refrigerant lines from the cooling unit, c) remove the cooler grommet, d) remove the expansion valve

The manual does not explicitly say to remove the entire Cooling Unit (3 hr job taking apart most of the dash) to access and replace the expansion valve. For other tasks such as R&I of the evapoator (page ATC-124) it actually does say to remove the cooling unit. So not sure if removal of cooling unit is req'd or if the manual just fails to state it. Unfortunately cooling units on gen 6 is not as accessible as the older gens are.

Which leads me to a few questions:

1) Does anyone know if to replace the TXV on a gen 6, would the cooling unit need to be removed from behind the instrument panel or can the cooler grommet be removed from the engine side of the firewall and the valve accessed through the engine compartment? I hate to take apart the whole dash if I don't have too.

2) Is it possible that the TXV would make noise if the system is low on R-134? I'm wondering if maybe I have another hose leak that is causing the TXV sounds I hear. My first hose leak caused no sounds, just warm air.

Thanks for reading and I appreciate any knowledge you are willing to share.

UCFAlumni2000

Follow-up: I was able to fix it. My r-134 had uv dye mixed in. I went under the hood at night with a uv light and inspected all the hoses. Almost immediately I found a leak on one of the high pressure hoses that goes from the compressor to the radiator/condenser. After that I used hvac manifold gauges to check high and low pressures. Both were lower than spec. I used my local shop for the recovery evac and recharge of the r-134 and I did the rest. My plan going in was since parts were cheap i was going to replace the hose, txv, and accumulator drier. Rockauto.com had best price on everything. Hose was very easy took 5 min. Next was the txv. I was able to access it from the engine side however the grommet was starting to fall apart when I tried to remove it. I didn't want to get pieces of the grommet in the txv so I chose to leave the old one in. If you ever had to replace it if the grommet comes out easy then the txv is simple to replace from engine side, if not then you will have to pull the dash apart to pull cooling unit to do it right. Next was on to the drier, this took 30 min. It is fairly simple but you have to be very careful when removing/tightning the bolt that holds the lines into the drier. Those lines are very small and bend easily and can be broken easily, they are aluminum I think. You have to really hold the cylinder tight so it doesnt spin when working the bolt. Same thing when pressing the new one on, hold those lines tight, two people make this job much easier. Make sure you use mineral oil to lube up all orings before pressing in any fittings. After hose and drier R&R and recharge of system, I have ice cold air again with no leaks. So back in my OP I was wondering if low refrigerent can make the txv noisy, the answer is yes it can. The noise does not mean necessarily that the txv is bad.

m86stanggt

Has anyone changed the expansion valve from the engine side successfully?

need to change mine on my 05 cause the compressor went. I am sure its clogged from the compressor dying