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Anyone out there familiar with the 66 factory a/c?.......i've replaced condenser,rec/dryer,all hoses & clamps,compressor & muffler assembly.Had the system recharged w/r12. Low 28/high 225.Sealed/corrected all leaks & the temp @ the a/c duct is only producing about 61 degrees.(the only difference is that someone in the past(Bubba) replaced the STV with a POA)...seems STV's are hard to come by.Any thoughts on the high temp of 61? and/or what's the problem? My understanding is that the POA's were introduced in 1967.
Ken......seems to be working....we replaced the heater control valve unit that is mounted on the firewall, all hoses & vacuum lines & vacuum valve behind glove box.
I have a 65 w AC, very similar to 66 but little differences. I always remove and plug the vacuum line going to the heater valve if no heat is desired, that way you will not get any warm coolant. The best outlet temps I get with mine are about 48 using 134 and now about 42 using R-12. Something is definitly wrong. Don H.
First, I'M not so sure a STV can be simply replaced with a POA with out other mods. That said, I'm gonna try to make this as simple as possible than direct you to where you can find more info and an up dated version of the POA or rather a POA eliminator kit. The hi/low pressures sound good. So the system is charged and circulating. Is the temp control on the dash vacuum operated? From your post I would assume yes. After the systems on for 15 min or so to stabilize can you feel the cold line going to the evaporator(careful theres a hot line there too)? It should be real cold. If thats the case I'd say the mixing door is open and heat from the heater core is getting in. Check that the door is closed when the dash switch is in the full COOL position. Its either not adjusted right or its not getting a vacuum signal. Thats as simple as that gets. There could be some issues that arent easily explained such as was the original suction throttle valve manual or vacuum? Hopefully the later. I believe starting in 66(dont know exactly when in 66) the vetts(Cadi,Eldo,Toro etc...) STV had a absolute vacuum regulator to prevent freeze up of the condensate on the evap core. Going from the STV to a pilot operated absolute valve(POA)would require the proper expansion valve,(internally or externally equalized?), equalizer line etc... Basically your system may be charged and circulating but the freon isnt being controlled or restricted to stay in the evap coil long enough to cool. Thats the job of the STV or POA and expansion valve. Simular to removing the thermostat in the engine-not enough regulation/restriction to dissipate heat in the radiator. If it is just the door problem great right!? If its a parts incompatibility than call the experts in. I use ClassicAutoAir(.com) out of Florida. They have all the right parts and the knowledge to get the right parts in there so your system works. Ask them if you could just put a POA eliminator kit in. I think that will work but it wont be original for judging if thats a concern. I'm sure they should have STV if you need to go that way too. Let us know how you make out.
Thanks Dave, thats alot of info! as to the STV...when purchased this car seems to have the POA but to answer your question the STV should have been vacuum operated...as to being the right POA & expansion valve.....who knows....seems Bubba & the whole clan worked on this one!...been a long year plus ...getting this one in shape....will check with ClassicAutoAir.com......I've replaced all the A/C parts in the engine compartment except for the ex. valve & POA.....I'm getting the feeling that all will be replaced in the end.... hope it's not in the heater box or evaporator end ......BTW: it's cold going to the evaporator...temp comtrol is cable operated w/vacuum line to heater cut off valve(which is new).....will keep you posted...
The cable is closing the door completely? There shouldnt be much if any heat in the heater core with the vac operated valve on the heat line off(not a vette expert yet. I know Olds has it screwed into the intake vs in-line). Do you feel heat getting by the vac valve in the engine compartment. I've seen bad vac valves outa' the box where the valve never seated. And the mystery continues.....
Have you had the inner box apart and replaced all the door seals and verified that the control cables fully open and close all the air doors? It's a "re-heat" system that directs cold air leaving the evaporator coils through or around the heater core (to modulate discharge air temperature), and if the doors don't seal effectively to the housing, you'll never get 40-degree air from the outlets. I can almost guarantee that NONE of the air doors are sealing properly after the 40-year-old cheap foam seals disintegrate and fall off. Even if the refrigerant system is operating properly, the air management system has to work also in order to produce COLD discharge air.
no.....haven't had the inner box out yet & I'm with you....more that likely the seals are bad, but.....with the heater vac. valve working(New)....which should cut off water flow to the heater core = no hot air by design.(don't think the main problem is in the heater box)..Spoke with Classic Auto Air today....their concern is that they feel the low side @ 28 is ok...but the high side @225 is WAY TO HIGH!Instructed me to cool down the condenser(to eliminate a bad condenser, clutch fan, etc...all new by the way) with a large fan or run water across the condenser & see if the cooling temp @ the air duct would drop...I did (run a hose across the condenser)....not the case..so seems those parts are working.However,I did notice that when I first start the engine & turn on the A/C it seems to blow Cold....but after running for a short period of time, the air temp warms up....noticed that the POA & the low side start to ICE up...checked sight glass...no bubbles....any ideas??
Hi Bob,
I know you said the water control valve and switch behind the glove box are new, but if hot water is leaking past the valve you will never get the temp. down. The easiest way to check this is wrap a shop rag around the heater hose and clamp it off with a "C" clamp or large vise grips. This would take about 5 minutes and you would no once and for all if that the problem.
Good Luck
Page Campbell
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