AC increases temp while sitting idle, blows 60F while driving

[pluto]

Replaced compressor and fan clutch last year, this year the Thermal expansion valve , but same results. Outside temp 95F , Pressures at idle low side 60 psi (pipe not cold), High side 220psi (pipe hot), at idle vent blows at 70F. I drive down the road 50-65 MPH and temps drops 58F. I pull over and sit idle shoulder , vent blows 72-78F aftter 10mins. Not maintaining cold air. any guidance would be great. Before I replace AC condenser, seeking advice

 

[pluto]

this is 2009 Expedition Eddie B model, dual AC, build date Aug 2008

 

[Hamfisted]

Did you measure your freon weight when you refilled the system after pulling a good vacuum ? Sounds like it's overfilled. Your low side should be 30-40 psi , high side 200-250 psi. Not enough pressure spread in the system.

 

[Trainmaster]

Frankly, my 2008 performs nearly exactly in the same way. I always considered a 20 degree temperature drop out of the vents to be okay. I never checked the pressures but just thought this was how these things were designed to perform -- rather lousy to conserve gas.

 

[Timo2824]

Did you pull a vacuum on the system after changing parts? Reason to do that it to remove none condensables from the system. They will cause higher pressure on the system and you'll never get the performance out of it because it will hit high head pressure often.

Next question, mechanical or electric fans? Mechanical fans won't pull enough air at idle if it's hot outside, especially if they're not locking up correctly anymore. At 95° ambient they should be making lots of fan noise with the AC on.

 

[Motorcity muscle]

Good deep vacuum is key, as Tim stated, along with a new filter drier. Would pull the upper radiator shroung and rinse out the condenser coil.

 

[pluto]

Several questions above:
Yes I vacuumed out the system for 2 hours down to negative pressures, let the leak up for 20 mins. No leak , gauge did not move
Yes I measured the freon going in, 2.5 cans of 12oz each. The truck hood says 34oz. I think I'm there , perhaps not over full
This truck has a clutch for the fan which I have monitored, the clutch is engaging cause I can feel the extra air flow and noise. Clutch replaced last year as a proactive measure
I thought the pressure on the low side was high too, but found some charts for Temp Vs pressure on low and high side. I seem to be in the right range for 95F outside
When i rev the car up to 1000 RPM the pressure drops to 45-50PSI on the low side, dont recall the high side.

 

[pluto]

I did vent the whole system to replace the expansion valve, I assume that means its empty and needs to fill to 34oz.
That said, prior to putting in the last 6oz or so, I was monitoring the cabin temp (AC on high, AC temp set to 60F, all vents open, rear AC ON w/ same setup)
The temp in the cabin after 10-15mins only go to 70F (24oz), so I put the remaining 6oz in thinking to would drop further. Prior to the last 6 oz or so the pressure on low side 50PSI high side 200PSI. Only change after last 6oz was low side increased to 60PSI high side on increased a little.

 

[pluto]

i'm think I may have a weak compressor or some restriction
For restriction what the best way to test , temp probing the condenser inlet and outlet , temp probing the evaporator inlet and outlet
Can the condenser be cleaned If I remove it ? Is the freon traveling through the condenser serial or parallel throughout

 

[Yupster Dog]

I did vent the whole system to replace the expansion valve, I assume that means its empty and needs to fill to 34oz.
That said, prior to putting in the last 6oz or so, I was monitoring the cabin temp (AC on high, AC temp set to 60F, all vents open, rear AC ON w/ same setup)
The temp in the cabin after 10-15mins only go to 70F (24oz), so I put the remaining 6oz in thinking to would drop further. Prior to the last 6 oz or so the pressure on low side 50PSI high side 200PSI. Only change after last 6oz was low side increased to 60PSI high side on increased a little.

i'm think I may have a weak compressor or some restriction
For restriction what the best way to test , temp probing the condenser inlet and outlet , temp probing the evaporator inlet and outlet
Can the condenser be cleaned If I remove it ? Is the freon traveling through the condenser serial or parallel throughout

You have not mentioned putting oil back in the system. Just wondering if you did.