need some A/C help

[88911coupe]

Follow on to this Prestite issue. On my 88 there was tape all over the place. Is that good or bad or not an issue so long as the bulb is in contact with the expansion valve and insulated itself?

[Barrpete]

Originally Posted by 88911coupe

Follow on to this Prestite issue. On my 88 there was tape all over the place. Is that good or bad or not an issue so long as the bulb is in contact with the expansion valve and insulated itself?

I don't think that would be an issue. Not to confuse the issue, but there's also a couple different styles - some have a loose bulb and some have the bulb attached directly to the evaporator outlet in what looks like a fitting. It's been at least 4 years since I replaced mine so my memory is a little fuzzy as to exactly which style I have. Either way, as long as its insulated with the tape it should be good.

[j930]

mines connected for sure.

[j930]

so we have 36 Oz of freeze 12 in. it cooled to 46 with a outside air temp of about 98 today, however it only cooled for about 5 minutes then the temp went up but the compressor was still running. we had the ball in the site glass floating after putting in the last few ounces but when we got back it was not floating any longer. then after sitting at idle for maybe a few minutes the temp came back down. it only got down into the mid 60's. the system holds another 11 oz but have read that you are to use 10% less in the system so we should maybe have 42 oz? would 6 more ounces make a difference? any one here used freeze 12 and know how much they put in. would the expansion valve be bad? bad compressor? any ideas are welcome. thanks guys. oh and the high side pressure was up to 325! so i don't think we can squeeze anything else in!

[brads911sc]

you should be using a conversion chart. xx ounces R12 = xx ounces of R134a, etc.
Also if you changed the components the original R12 capacity might not be accurate.

I usually fill based on high side and low side pressure. in fact i dont even measure the ounces. I am pulling from a 30 Lb tank so when its cold, low and high side presssures are good based on ambients.. im done.

never had an issue... sounds like maybe you have another issue? compressor staying on at higher rpm's? you have a griffiths on-off with the light that tells you if the compressor is working? evap freezing up? using a high output fan? if you shut the compressor off once it gets warm, and drive for 20 min or so and turn back on does it get cold? if so your evap is freezing. the rpm value may be conincidence...

[j930]

it cools down when sitting overnight, but after maybe 20 minutes it stops blowing cold, compressor is still going as i opened the rear hatch and its still humming along. after maybe 10 or 15 minutes it will come back on.

[brads911sc]

Here is what I would do. Drive it with AC running until air gets warm, shut the AC off off and drive it another 20 minutes (sorry youll just have to sweat), turn AC back on and drive 5-10 minutes to see if it gets cold. this will rule out the evap freezing up.

did you change the expansion valve?

[j930]

we did not change out the expansion valve, i wish i would have as it would rule that out and not waste 75.00 worth of freeze 12. but thats what its doing it will come back on after about 20 min.

[j930]

ok its getting hot out here again in phoenix so i am trying to solve this A/C issue. it will blow cold at start up. but when i start driving and lets say the RPMs are over 3K it immediately blows hot. compressor is running front condenser fan is working. could the expansion valve be my problem? as soon as the RPM come down it blows cold again?

[pharlap71]

there is more to high side readings than amount of refrigarant,ie, air moving over condensor, with the engine lid up no air is flowing over condensor unless you have electric fans so you will get high readings. Also as been metioned here volume in ozs is just a ball park figure. You can set a fan to blow over rear condensor and bring pressures down, also misting with water will bring it way down. Sounds like your evap is icing to me, low refrigarant will cause this.

[j930]

my high side pressure was higher than the book suggests. if that valve was not working would that cause this issue?

[Jim Sims]

It would appear you have moisture and probably also air within your system. The water is freezing in the evaporator, plugging the system and stopping the flow of the refrigerant. I wasn't able to discern what you initially did from your posts. If the system was open to air or air introduced by the charging procedure that could be the problem. Water gets in with the air. How old is the receiver/drier - has it ever been changed?

Your system likely needs to have the refrigerant removed and reclaimed (not recycled), a new receiver/drier installed (replace any refrigerant oil there in with whatever oil the refrigerant manufacturer recommends), the system leak checked followed by an evacuation for three hours minimum with a good 2-stage vacuum pump (capable of reaching 40 microns or less of pressure) with new clean vacuum pump oil. Then properly charge per the refrigerant manufacturer's instructions.

The small OD hose likely just means that the new line was made using reduced barrier hose - it has a thinner wall than standard barrier hose but the ID where the refrigerant flows is probably the same as the old hose.

Wear eye protection and charge the system with the car fully outside, not partially in a garage.

Good luck.

[j930]

so is the general consensus that the expansion valve would not cause this problem.. aim going to work on this next weekend and will order one if you guys think it might be the problem? I can get a ton of airflow over the rear condenser with some big fans i have. just getting together a list before the weekend.

[bazar01]

Originally Posted by j930

so is the general consensus that the expansion valve would not cause this problem.. aim going to work on this next weekend and will order one if you guys think it might be the problem? I can get a ton of airflow over the rear condenser with some big fans i have. just getting together a list before the weekend.

Do you have a manifold gauge? An expansion valve that is not functioning well or blocked due to a frozen orifice will cause a very low than normal low side pressure and a very high high side pressure.

[88911coupe]

I'm curious about the expansion valve issue as well. What is the difference between one that works with R12 vs. R134 or the other substitutes like Envirosafe etc.?

[j930]

yes we are using manifold gauges. and i will have to go back and read my old posts as i don't recall the low side being abnormal but the high was absolutely crazy. i know some of the guys wrote about airflow over the condensers and that has been verified and it seems that i have more than enough air flow. if i am idle at a stop light the cold air will start pumping away. but as soon as i start driving the cold air goes hot. compressor is still running but no cold. i would not think airflow would be the issue as when i am driving i don't see any abnormal engine temps. i am thinking its gotta be the valve? the car only has 40K miles on it and i am sure it s the original 84 valve? maybe they just go bad from no use?

[j930]

bought a new dryer and expansion valve. vacuuming down now will post results when done. hopefully problem solved!

[j930]

problem is solved!

[scottb]

What did you end up doing?

How much ES-12a (or Freeze 12) do you have in the system now?

What kind of vent temps are you getting?

[Joeaksa]

Did not see an answer to Scotts question. I am doing the ES-12 on my 911 now and wondering how much gas to use?

Thx, Joe