OEM AC question

[36chevy]

I live in Florida so it gets very hot here and my square is my dailey. I have the orginal AC but running a 5.3 from 2002 siverrado using the 2002 comressor and orginal clutch fan. In the morming or if its raining the AC is very cold. As soon as a get in any traffic the temp starts raising up to 79 degrees which is not comfortable.

Question is if I go electric will the increased cfm cool better and will that help with my ac problem. Also would going with an aluminum radaiter change anything.


Thank you in Advance
Jesse

[hatzie]

Electric fans will make it worse.
If the fan clutch is getting weak replace it.
Make sure you have the fan housing in place so the fan draws all of its' air through the cooling pack.
The cooling pack used to have waxed cardboard wings make sure the fan sucks air through the condenser and radiator.

If you have too much oil and any mineral oil floating around in the system it'll negatively affect your cooling.
Did you flush the hoses, evaporator, and condenser? The dryer is loaded with oil so you have to change it.

The R12 orifice valve is too large. It'll work with R134a but it won't cool as well. The Corvette guys use the Ford blue orifice valve.

If your refrigerant charge is too low the evaporator will freeze up. I recently posted a method to charge an R12 system with another refrigerant and not have too much or too little refrigerant be it Hydrocarbon or R134a or HFC152 or ...
https://www.67-72chevytrucks.com/vbo...1&postcount=10

[Dead Parrot]

Other things to check:
Make sure the heat/cold flapper is fully shut. Doesn't take much slop to let a lot of heat escape into the AC side. The heater core is normally hot all the time so the flapper adjustment is important. It is behind the glove box.
Is the vacuum operated door on the passenger side working? That is the one that lets the recirculate feature work. Reusing the already cooled and dried air from the cab helps with cooling. It should be open when you have the AC on "Max AC" or similar. Labeling varies for different years.
Probably a silly question but when the engine swap happened, did the vacuum for the cab controls get connected, including the vacuum ball?

[36chevy]

Very good points. I did change all accessable parts. Fan clutch ,Dryer, orifcae tube, evap flush.

It never occured to me that these systems are made for R12. I replaced the oriface tube with oem part number. Iam going to start with checking the flapper this weekend.

Yes I did remove the vaccume ball.

ALso maybe there is a way to direct more air from the shroud.

[Dead Parrot]

If the cab AC control doesn't have vacuum, then the flappers are in the default position. Could have a detrimental effect on operation.

The ball serves as a reserve for those times when the engine vacuum goes low. The ball includes a check valve that lets it hold vacuum even if the engine vacuum goes to near zero.

If you removed the ball but did connect the cab to engine vacuum, possible the cab flapper valves are changing positions as you drive, based on how your source responds to driving conditions.

[hatzie]

Originally Posted by 36chevy

It never occurred to me that these systems are made for R12. I replaced the orifice tube with OEM part number. I am going to start with checking the flapper this weekend.

The OEM R12 orifice tube is a white .072" orifice IIRC.
R134a refrigerant needs a smaller size orifice tube hole than R12 to work effectively.
You need a .067 orifice rather than the original .072 orifice. The so-called "Ford Blue" orifice is .067".
It's roughly the same color as Ford blue engine paint.
Here's a Blue .067 orifice tube at AutoZone
Here's the same Blue .067 Orifice tube from NAPA

Hydrocarbon refrigerants, R290 & R600, do OK with the .072" R12 orifice tube but HFC152 or R134a definitely need a smaller diameter .067" orifice tube.

Originally Posted by 36chevy

Yes I did remove the vacuum ball.

The 1990's and later rigs used electric motors to drive the HVAC box flaps. When the throttle opens wider the intake vacuum drops. You need the vacuum reservoir, with a check valve in the vacuum line, to store vacuum to run the HVAC flaps. If you have low vacuum the flaps will not stay firmly in the selected position letting warm un-conditioned air to slip past the loose door.
Going down the flap door rabbithole... the HVAC boxes are 40ish years old so the flap gaskets aren't in the first flush of youth.

You should also have a check valve on the vacuum brake booster vacuum feedline or upgrade to hydroboost. IIRC this check valve is in the elbow into the vacuum booster bell.

Originally Posted by 36chevy

Also maybe there is a way to direct more air from the shroud.

GM used rubber or waxed cardboard flaps on the sides of the cooling pak to keep the fan from drawing air from the slot between the condenser and radiator. You could use rubber flaps or maybe closed cell foam??