ddahlgren

91 coupe converted to 134a a couple of years ago. For 2 years fine this summer blows 59F out of the center vent with no short cycle problems. Is it the charge or do I possibly have other problems that I can not afford. When converted changed oil fittings dryer orifice tube and blew 47 degrees and worked well enough for CT summers. Today it is 84F and 59 out of the center vent. I am not an AC guy and hope an easy fix. Could it just be low on gas though if it was I would think it would short cycle. No signs of any oil leakage and I can hear blend doors change as I set various modes from the sounds of things moving and the fan sounds as air is redirected and blow out of the correct places.
Dave

JackDidley

Check pressure. Probably needs a little 134.

pcolt94

If the compressor cycling off and on every few seconds, it just could be a low Freon condition. If it is, you can just add some Freon. But the better way is to get a gauge at least on the low side and see if it pulls down below 22 psi to rapidly to cycle off.

If you are not cycling the compressor and it is running, I would not add Freon as of yet. I would then look at things further and get a gauge on it and see what is happening.

Are any of the fat lines real cold or sweating?

engle1147

add some juice slowly (vapor) while watching the center vent temperatures...shoot for low 50's (if outdoor temps are under 90 F)out of the vent then leave it alone.

Using a gauge manifold set is the best way to go to see what's really going on.

ddahlgren

Ok an update I checked the compressor does not short cycle it never stops turning clutch engaged. Not being a cooling wizard please excuse the terminology if wrong. The condenser I think next to the radiator top line 147F lower line 128F top line coming from heater box about 53F Big can (accumulator / dryer?) both lines about 57F. It is 80F outside and system set on recirculate. I used a thermal probe on a mutlimeter. Center vent after 4 minutes on recirculate is 53F. Is this the best I can expect on a conversion. The car is much more comfortable on recirculate I do have to say.

pcolt94

I actually had a similar situation several years ago where all was working, it blew cols but just not cold enough. Just did not have that edge. Adding some Freon made the difference. The cold lines got colder and the accumulator really got cold. I did use gauges and is my experience. Can't guarantee adding Freon will help your problem but it might.

engle1147

Mines converted to the 134 and I run an uderdrive crank pulley(compressor runs a bit slower than stock) but my system works pretty well over all. 50-55F (just above idle) is just about what I get out of my vents on a ~93 to 100 degree day. When the outside temp is under 85F my vent temps are in the upper 40's.

53F @ idle from the center vent isn't that bad - it should keep you some what cool for the time being. The best thing to do at this point would be get a hold of or borrow a manifold gauge set to check the hi/low pressures before adding additional freon to the system.
Another very important step would be to ensure that coils of both the evaporator & condensor are clean promoting proper heat exchange. Ensure that the radiator is debris free/clean as well since the fan(s) must draw air through that area to get air moving through the condensor coils. Several aerosol type a/c coil cleaners ($5 a can) are available at your local home improvement store. The evaporator box has to be pretty much disassembled to gain access for cleaning but getting to both sides of the condensor is much easier by comparison.

ddahlgren

Hi engle1147 funny you mention underdrive pulleys previous owner put some on but only water pump and crank will retest at 1500 and see if different.
Dave

ddahlgren

Retest done at 1700rpm it blows 47F never mind...LOL off to find the new rattle that I got while cruising in South Hampton NY..sigh.. If ever at the east end of Long island ny please drive through Shelter Island. This is a town that has an American flag on virtually every phone pole on every major route! My kind of town! I asked a guy on the ferry about it and he commented it was a very patriotic place and a very bad one to speak poorly about the USA!!!!
Dave