A/C not as cold while sitting still

[xrunner123]

I replaced the blower fan in my GN with a 12 dollar replacement from the auto store and it blows like a tornado now. Easy to change too.

What fan did you place it with? Do you know what the part number is?

 

[charlief1]

Ford!

It's an old trick to help cool the system. GM used 1 hole in the orifice tube and ferd uses 2 holes in the tube. The faster rate of change from liquid to gas drops the temps faster. It's refered to as "change of state". There are 3 changes of state in an AC system. Low pressure gas to high pressure gas to high pressure liquid. Compressor takes it from a low pressure gas to a high pressure gas. The condensor changes it with heat exchange into a high pressure liquid, and the orifice/expansion tube takes it to a low pressure gas. Going fro a high pressure liquid gas to a low pressue gas is where the cooling takes place.

Think about it like a can of spray paint. Have you ever noticed the can gets cooler as you spray it? Same principle.

 

["Turbo-T"]

When I had my car retro-fitted we put in a blue (Ford) orifice tube. With a Cotton's front mount, stock fan, stock condensor, Aladin aluminium rad, car never gets over 180*, fan comes on and stays on at 160*, the a/c temp centre vent is in the 40's even at idle, I have seen 36* while cruising, I used the stock compressor, new accumulator drier, and the 4 seasons retrofit kit. Your car is running on the hot side.

I tried doing a search for you but came up empty, there was on old post stating that if you did an r-134a conversion the blue orifice tube was recommended. That's why I used it.

I read somewhere to use the red orfice, not sure where.

 

[bose]

Ford!

I looked in the factory repair manual and if running R12 the suction pressure can vary from 23-35 psi and the high pressure can vary from 170-245 psi. The pressure will be much lower on a 75 degree day that it will be on a 95 degree day. I don't know what the pressure should be for 134a but I am sure if you goggle it you will find the answer.

 

[Steve V]

I used the blue and it worked great,used the red not so much. So the blue is the one to use for sure.

 

[TurboBob]

I switched from the stock mechanical fan to a dual electric on my Tahoe and the temp at the vents went down 10 degrees at idle. My Buick was running hot with the stock electric fan and when I switched to the SPAL dual setup it made a huge difference. Just because the stock electric fan is running does not mean it is moving the amount of air it is supposed to. Electric fans get weaker with age and don't pull the air they are supposed to. Your car is running on the hot side anyway. I would switch to a dual electric fan setup and see what happens. Couldn't hurt.

I'd like to hear about that Tahoe setup some, we have a 99 2WD Yukon, and its going to be hot this summer.

How are you controlling the fan? Wiring, etc....

Bob

 

[Flyin Brian]

What fan did you place it with? Do you know what the part number is?

I bought the VDO brand blower motor from Oreilly Auto part number PM105 for $14.99. (thought it was 12 dollars but just checked) It was super easy to change out. Just disconnect the wires from the old blower motor on the ac box under the hood and take out the bolts holding it in. Switch the fan wheel from the old one to the new one and re-install. I think my old one was the original and it was weak. The new motor blows way harder.

 

[Flyin Brian]

I'd like to hear about that Tahoe setup some, we have a 99 2WD Yukon, and its going to be hot this summer.

How are you controlling the fan? Wiring, etc....

Bob

I have a dual electric fan setup on an aluminum shroud with an adjustable on/off thermostat. I bought it years ago from Permacool PN 19514. It was $450 ten years ago. I don't know if they still make it or not but it is a nice piece. Pulls a ton of air. The adjustable thermostat is a contact type sensor that touches the radiator core for temp reference. It also has a trigger wire to turn it on when the AC compressor kicks in. It pulls like 17 amps so I have it hooked up with heavy wire and a heavy duty Bosch 30 amp solid state relay with a 30 amp fuse. I also ran an override switch into the cab so I could run it whenever I want. 100000 miles later it still works great.

 

[TurboBob]

wow, thanks.

B

 

["Turbo-T"]

I thought I'd take the time to post my outlet temp readings. It was 90 degrees outside, with the car sitting in the drive way after being pulled out of the garage.

I used a digital thermometer (like what you'd use to test how hot or cold your food was) I took the readings from the center vent, with the tip of the probe just outside of the black vent.

With the a/c in the normal mode, the coldest it got was 55 degrees. With the a/c in the max mode, the coldest it got was 48 degrees. Though it doesn't feel that cold either time, IMO.

 

["Turbo-T"]

I also forgot to mention I took all of the readings with the fan on medium high, and both doors closed.

 

[HouTX87]

30–35°C (86–95°F)

Below 30%

257–359 kPa (37–52 psi)

1320–1610 kPa (192–234 psi)

17°C (63°F)


30–50%

267–375 kPa (39–54 psi)

1340–1650 kPa (194–239 psi)

18°C (64°F)


Above 50%

281–399 kPa (41–58 psi)

1360–1710 kPa (197–248 psi)

20°C (68°F)

 

[HouTX87]

That info is from the GM A/C performance test chart for r134a with ambient air temperature 86-95 degrees F.

Relative humidity %
Low side pressure
High side pressure
Maximum discharge temperature

 

[Dreamcar86]

I have a dual electric fan setup on an aluminum shroud with an adjustable on/off thermostat. I bought it years ago from Permacool PN 19514. It was $450 ten years ago. I don't know if they still make it or not but it is a nice piece. Pulls a ton of air. The adjustable thermostat is a contact type sensor that touches the radiator core for temp reference. It also has a trigger wire to turn it on when the AC compressor kicks in. It pulls like 17 amps so I have it hooked up with heavy wire and a heavy duty Bosch 30 amp solid state relay with a 30 amp fuse. I also ran an override switch into the cab so I could run it whenever I want. 100000 miles later it still works great.

Looks like the price has gone up a bit on those fans. They are now over $1200

 

[TurboDave]

Ford!

Ya, you know, the really high quality stuff! Sorry, couldn't help it, I'm a Ford guy.

 

[87-WE2]

Jeez, TurboDave - after 10,000 posts we find out you're a FORD guy!!! At least your taste in GM vehicles is good!!

 

[turbofrank]

After reading thread nobody asked t-top or hardtop? If t-top car interior stays hotter.

 

[jimski]

I did attach my manifold gauge to the test ports on the a/c. On the low (suction) side it ranges between 35 and 40 psi. But on the high (discharge) side it typically sits at over 200 psi.

When I did the retrofit, I used 4 of those 12 oz cans of refrigerant plus 8 oz of pag oil for the 134 conversions. I also swapped out the compressor, drier, orfice tube (red one) and drew a vacuum for an hr (held great overnight) last summer.

I've also checked the condenser and didn't see any obstructions.On another note, my car does typically shoot up to 212 on a hot day if sitting in traffic. I run a stock radiator but I run a 160 degree T stat.

Speaking of condensers, do they make a bigger one that is for R-134a retrofitted cars?

134 head pressure is a little higher than 12

 

[JimP]

Another suggestion, instead of R134a as a refrigerant there are now R-12 alternatives, they work better, run at lower pressures and produce cooler vent temperatures thatn r-134a in a retrofitted R-12 system.

If you were thinking of evacuating the system and recovering the r-134a, replace the orifice tube ($3) for a Ford blue you can use then use the Duracool 12-a, Pro-cool or freeze 12, ES-12a ( http://autorefrigerants.com/co00033.htm) they all claim lower vent temperatures, faster cool down and lower pressures.

 

[turbo john FL]

i am putting old r 12 back in my car will using that blue orrifice tube from a ford help that run cooler with the r12 also ?? thanks !