cgillum

Help!
My mechanic flushed the system, replaced the A6 compressor and drier I bought from eckler for the 1970 BB, converted the low side fitting to R-134a, put in required oil and refrigerant but the A/C is not blowing cold. Does anyone know if you need to change the POA valve due to the conversion? Or could it be the hot water shut off valve or A/C expansion valve?
Thanks in advance
Chuck

dtamustang

i used my original POA valve when i did my conversion and it worked fine,i have vent temps in the mid 40s

ezobens

R134a requires you change your hoses to the newer 'barrier' style hoses that won't allow R134a to escape thought the lines like your old R-12 lines will. I've also heard that if you're running a POA valve, it needs to be adjusted to work with the higher pressures required for R134a.
Also, if you didn't replace the condenser with a new parallel flow condenser, it will never be as cold as your old R-12.

Just evacuating the R-12 / oil and replacing it with R-134a and oil is not the proper way to do the conversion- If that's all they did, you'll be disappointed until it's done the right way.

Any reason why you replaced the R-12 with R-134a to begin with?

TimAT

If he charged it to the volume specs printed on the sticker, it's probably overcharged too. 134 takes 10% less volume than R-12.

C6DuffMan

Did it work OK before the work?

With R134a, the POA should be adjusted for optimal performance. Many people just swap in R134a and they say it's fine. Regardless, it should blow at least somewhat cold even without adjusting. Maybe there's too much oil, over charged, under charged.

This forum has loads of good info on AC; http://www.autoacforum.com

cgillum

I bought the car with a seized compressor. The guy I bought it from said it worked two years prior? So, I ordered the compressor and drier from Eckler and my mechanic flushed the system replaced the parts put the required R-37 (i think) oil and he said rule of thumb for conversion was 85% but the system took about 90% before the drier sight glass stopped bubbling. everything works just not cold.

lonebull

chuck-you have your hands full retrofitting a c3 to r-134! you will have to do a lot of searching on the forum & lots of study- most members won't answer the same question twice & this is a huge problem for the c3. if you do a search you will find such info as 1. install parallel flow condensor 2. replace all hoses w/barrier hoses 3. add adjustable poa 4. clean evaporator 5. check/ replace all seals 6. check freshair mix actuator 7. floor must be heavily insul. to keep motor heat out 8. check hot water cut off 9. replace blower motor w/c4 unit to increase volume of air to vents 10. check the seals on the vent sys. behind the dash 11. add elec. fan to cool condensor 12. replace expansion valve or orifice tube ( gets clogged up) 13.check elec. connectors & ground wire to blower. & the list goes on- 1 guy said move to alaska! you have to find an a/c man who knows what he is doing. how did your mechanic explain WHY you didn't have cold air? you should have at least been in the high 50's but you need to be in the mid to hi 40's. search & study my friend. tell us where you live- maybe someone knows a reputable shop in your area. ps some of my points were already mentioned- not stepping on any toes here. what you're after isn't cheap especially if you have to hire it done. lonebull

roger3

I have a 71 and 76 vette. When I bought my 76 the previous owner had done about what you did (flush, new drier, and R-134). It would blow slightly cool but not cold (60 degree vent temps).

When you first crank the car and run the AC system (before the engine heats up everything) it will blow its coldest. If it doesn't get down in at least the low 50's, you got problems.

I found these problems with my 76:
1. Evaporator box was full of leaves, acorns, etc.
2. The box around the evaporator core had a whole in it so heat from the exhaust manifold was coming in.
3. My my heater shut off valve was not working.
4. Seals in evaporator box and air ducts were deteriorated.
5. Trash and debris mixed through out hoses, evaporator, and condensor.
6. VIR valve had not been recalibrated for R-134
7. Insulation under transmission tunnel was missing.

After fixing these things, and recharging with R-12, blows mid 40's out of the vents.

When I bought my 71, the AC compressor was locked up and rubber AC hoses had been cut off. I took everything apart, flushed each component, went back with new seals everywhere, and it blows mid 40's out the vents.

I am not an AC expert, but have read that experienced ac mechanics can pin point your problem by feeling which components are hot and which ones are cold, and by reading the pressures on the AC guages. You might want to take it to a different mechanic before you dive in. But if you want to fix it your self, it's not that hard. I did all the work myself, then took it to a good mechanic shop, they pulled a vacuum and checked for leaks, filled it with oil, filled it with R-12 freon, and its been working great for 2 years now.

MrForce

Thanks for this! I cut and pasted it into my project folder.

cgillum

I live in chesapeake Virginia so if anyone knows a good A/C shop let me know