A/c Charged But Still Not Very Cold When Driving

[blessed]

What do you think guy's?

I've got a 91 LS 400 and just had the AC charged. The service invoice states they Added Freon to Full Level, Took 1.5lbs. System Holds 2.42 Total. High Presure Side is at 178 psi, Low Side is at 29 psi. Vent temp at 33 degree's.

However, when your driving down the road the AC begins to blow warmer air. When at a stop light or at an idle it's nice and cold. What's even more interesting is the fact the two center vents are blowing considerably different temperatures. The driver vent is a lot warmer than the passenger vent. ????

What's causing the AC to not blow COLD air when driving?

Thanks in advance for your suggestions.

S

[Threadcutter]

What do you think guy's?

I've got a 91 LS 400 and just had the AC charged. The service invoice states they Added Freon to Full Level, Took 1.5lbs. System Holds 2.42 Total. High Presure Side is at 178 psi, Low Side is at 29 psi. Vent temp at 33 degree's.

However, when your driving down the road the AC begins to blow warmer air. When at a stop light or at an idle it's nice and cold. What's even more interesting is the fact the two center vents are blowing considerably different temperatures. The driver vent is a lot warmer than the passenger vent. ????

What's causing the AC to not blow COLD air when driving?

Thanks in advance for your suggestions.

S

S:

Filter, Filter, Filter................

(Cabin Air Filter................is it clean?)

Do a search on this site for "cabin air filter"..............There's plenty of info here.

[SKperformance]

I would also check for vacuum leaks to the air control dampers.

[blessed]

What do you think guy's?

I've got a 91 LS 400 and just had the AC charged. The service invoice states they Added Freon to Full Level, Took 1.5lbs. System Holds 2.42 Total. High Presure Side is at 178 psi, Low Side is at 29 psi. Vent temp at 33 degree's.

However, when your driving down the road the AC begins to blow warmer air. When at a stop light or at an idle it's nice and cold. What's even more interesting is the fact the two center vents are blowing considerably different temperatures. The driver vent is a lot warmer than the passenger vent. ????

What's causing the AC to not blow COLD air when driving?

Thanks in advance for your suggestions.

S

S:

Filter, Filter, Filter................

(Cabin Air Filter................is it clean?)

Do a search on this site for "cabin air filter"..............There's plenty of info here.

Thanks Threadcutter......Did the search and took off the panel only to find out the 90-92 LS does not have Cabin Air Filters. <grin> Do you have any other suggestions?

I would also check for vacuum leaks to the air control dampers.

Thanks SKperformance..... Did a search for "air control dampers" and nothing came up (other than this thread) Is this something that must be done at the shop with special tools? Sounds like it is.

Is a vacume leak simple to fix or complex (expensive)?

S

[bigfatlexusman]

I would like to know also my 94 ls 400 is blowing hot on the driver side and cold on the passenger side, any help would be appreciated

[LScott400]

On your '94 start with How To Remove Cabin Air Filter, For 1993&94 LS400.

[LScott400]

Blessed,

33 degrees at the vent suggests to me that once your running down the road with full air flow through the condensor that the expansion valve is freezing up. Once you come to a stop, the heat transfer across the condensor is less efficient allowing the valve to unfreeze so the freon gets to flow again and thus the a/c blows cold again. With the a/c on I would get someone to hold the accelerator down maintaining 3000 RPM, set up a box fan on high in front of the condensor and then look under the hood for the Expansion Valve and watch to see if it frosts over. If so, you could run a hair dryer on it and I bet the air coming out of the vents will start blowing cold again as the valve warms up. This would mean the system is somewhat undercharged with freon. I'm not sure what to think about the 2 center vents blowing significantly different temperatures.

I don't know if it is of any value, but there is an old Thread with different symptoms. If you wade through it, there is discussion of air mix doors.