New AC System Doesn't blow cold enough / 68 Polara 383

[GMPolara]

I'm having some problems with my newly rebuilt AC system. It's not blowing cold enough. I've changed it over to 134a.

Simultaneously, my engine has developed an overheating problem. I attribute this to not having installed the correct water pump. This engine (383) has two water pumps available for it. One of which is specifically for car's with AC. Which is not what I have in there right now. I'm fixing this currently.

I'm thinking that maybe an extra fan in-front of the Condenser may help with my AC problem. But I'd like some other opinions on this. CALLING ALL HVAC FOLKS!

Here's a video that goes through the details about the new AC system:

Dropbox

 

[Toolmanmike]

Do you have a clutch fan and a shroud on it now? It should all be working properly and may help your a/c and heating up problems as long as all is well with your cooling system. I wouldn't condemn the pump until you check out the rest of the system.

 

[CBODY67]

With the a/c 6-blade water pump, the drive ratio also increases to move about the same amount of water as the 8-blade non-a/c pump does at the lower drive ratio that pulley set has.

Is the system charged to about 90% of the R-12 charge level with R-134a? Is the "lesser cooling" happening sitting still or on the road? Stock condenser or an R-134a rated mass flow condenser?

CBODY67

 

[GMPolara]

Do you have a clutch fan and a shroud on it now? It should all be working properly and may help your a/c and heating up problems as long as all is well with your cooling system. I wouldn't condemn the pump until you check out the rest of the system.

Yes, it's got a clutch fan and a fan shroud. I currently, have the a new clutch in hand. The old one was working but a it's action was a little too loose for my taste.

 

[Toolmanmike]

Yes, it's got a clutch fan and a fan shroud. I currently, have the a new clutch in hand. The old one was working but a it's action was a little too loose for my taste.

Bolt that baby on and see what happens. If they are loose there's a good chance it isn't locking up when needed.

 

[GMPolara]

With the a/c 6-blade water pump, the drive ratio also increases to move about the same amount of water as the 8-blade non-a/c pump does at the lower drive ratio that pulley set has.

Is the system charged to about 90% of the R-12 charge level with R-134a? Is the "lesser cooling" happening sitting still or on the road? Stock condenser or an R-134a rated mass flow condenser?

CBODY67

I hear you on that water pump. I'm just grasping for straws.

I've put about five six once cans in. But I had a leak initially. I'm not sure how much leaked out. Currently, I'm just going by the gauge pressure. Per the low side gauge, I'm at 50psi @95F. I would guess I'm overcharged but the last can I loaded went in like duck shite. Also, the compressor is still nice an quite. Not exactly a scientific explanation, but hopefully that gives you the picture.

The condenser was rated for R134a. It cools best while going down the road, appox. 65F. It seems to get warmer when I accelerate. At idle it's near cool but not cold 65/70F.

Things that I feel might be a problem are that the new Evaporator is OEM design and so is the expansion valve.

 

[3175375]

What pressures are you seeing when the system is on, windows down and set for full cold and max A/C? Also, report the register (interior vents) temperature.

 

[CS43FI]

I have also seen capillary tubes taped on low side tube surface and heard them working. Factory material shows that they originally go inside thermowell immersion to avoid engine temperature to mess things up. Judging by the video, I suspect there is no possibility to get two capillary tubes mixed up?

 

[Big_John]

I've put about five six once cans in.

Way too much.

I'm not an A/C authority so I can't give you much help, but I do know that over-charging with 134a is not going to help. There's some formulas for pressure, but I think most just measure output temperature and charge until it's blowing real cold. Too much and the output temperature starts warming up.

IIRC, it takes about 2 1/2 cans for me to fill my A/C with 134a.

 

[Ross Wooldridge]

System is overcharged for sure.

R134A should be charged at about 55% of the original charge weight of R12, and go up from there.

Shroud will help too.

 

[lemondana]

Put R12 back in it!

 

[Unix]

My 71 2bbl 383, with AC switched to 134 blows cold, and no overheating problems with engine, even in drive in an hour long traffic jam. I do have original shroud, original fixed fan w/o clutch.

 

[3175375]

What pressures are you seeing when the system is on, windows down and set for full cold and max A/C? Also, report the register (interior vents) temperature.

My requests seem valid…

 

[65sporty]

Late to the party. What is the systems total capacity? Five 6oz cans is only 30oz, not even 2lbs. Most of these older systems took 4lbs. When we first started doing A/C conversions from R-12 to R-134A, 80% was the rule of thumb as a starting point. I have used up to 100% in some systems. I always use a gauge set to see the pressures so I know what is going on, but I have the advantage of access.