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.

 

[pluto]

Interesting you would bring that up. I did not put oil back in, I pumped the system out a room temp and the car should not been start for over 24 hours, so my thought was it was only Freon being pulled out not oil since is was under pressure of only 85PSI ambient temps
You think I should add oil into the system? How much, like 2 oz? I think Walmart sells a small canister that oil only.

 

[Hamfisted]

Auto Zone sells the PAG 46 in 3 oz. cans.

3 oz can of PAG 46 at Auto Zone


I still say your low side is too high. Try spraying a mist of cool water from the garden hose in the condenser and see if your temps / pressures improve. Could be a blockage in the condenser, but you'd have to pretty much do a FLIR temperature scan of the condenser to see it.






.

 

[pluto]

I can try the water hose suggestion.
Do you know if the freon travels through the condenser in serial or parallel paths ?

 

[Hamfisted]

I can try the water hose suggestion.
Do you know if the freon travels through the condenser in serial or parallel paths ?

Parallel flow ...







.

 

[pluto]

Hamfisted - I install my gauges while at idle ambient temp 95F , Low side 60-62PSI, High side 210-220PSI, in cabin temp 72F~. I started to hose down (not a mist, more low pressure hosing it down) the front end through the front grill. I did that for about a minute, walk around the window to see my temp gauge, temp did drop after 2 minutes, but also the gauge really dropped
1) Low side 42PSI, High side 150PSI, in cabin temp started dropping to 62F~
2) started to rev up the truck to 1000 rpm for ~1 minute , Low side 38PSI, High side 170PSI, in cabin temp 60F~
3) started to rev up the truck to 1500 rpm for ~1 minute , Low side 30PSI, High side 180PSI, in cabin temp 58F~
These number look a lot better due to the hosing down the front end thru the grill. Not sure if the water caused some pressure expansion and release of internal clogged with temperature change (thermal expansion). By this time I needed to run in for a conf call at 8pm, I will test again tomorrow mid morning once the ambient temps hit 90F or higher.

Hamfisted , check this out . Prior to doing above tests, I noticed the suction line from the condenser to the front expansion valve has a "Y" (front and rear AC units). The Y section going to the rear ac is cold, the section to the front expansion valve is warmer with the front AC on. Not sure why the this .I turned on the rear AC, that section of the suction line started to warm up to match the other Y section. At this time the cabin temps were 72F after 10 minutes of idling the truck with ambient temp 95F , Low side 60-62PSI, High side 210-220PSI. At first I was thinking, there is clogged in the evaporator cause I replaced the Expansion valve already. Bu that did not explain the reason for the suction line temp to increase once I turned on the rear AC. I would of thought the rear ac suction line would get colder. I that point I was confused and moved on to your hose test which I'm glad I did

 

[Hamfisted]

Why did you replace the compressor originally ? Did it come apart ? If so, debris may very well have gotten into the condenser and partially clogged it. These parallel flow condensers clog very easily and are generally replaced anytime a compressor sends it's debris into the system. Their passages are very small, and they're almost impossible to flush out adequately to continue in a refurbed system. Your pressures appear to improve dramatically when you sprayed water onto the condenser.


Condensers at Rock Auto


.

 

[pluto]

I replaced the compressor last year for the same issue having today, the new compressor improved and helped maintained temps in the mid / upper 60F while in traffic but this year the heat here is TX has been very high and very early in the year. This year it would not maintain below 70F, climbs more quickly to 85F and above while in traffic (stop and go situations). The old compressor once removed, oil was clean, but I could turn the pulley very easily, seems to have lost compressor. I still have and thought about a local rebuild, The replacement compressor was purchased from RockAuto along with expansion valve front (installed recently this year) and back.
I will continue to monitor the ambient temp Vs Cabin VS Low/High pressures
Thanks for the dialogue and ideas, when I go into it again I will replace the Condenser, remove the expansion valve and blow out the evaporator lines all the way to condensor and see what comes out . thats alot of work (take apart the front end) and trying to avoid , will see how it goes in the coming weeks once parts arrive

 

[Timo2824]

I'm going to throw this out there, as a former ford mechanic and current HVAC professional, take it to a shop. You're throwing parts at it and don't know what you're doing. If the system doesn't have enough oil in it, you'll destroy the compressor. If you put too much oil/leak dye in it, you'll coat the evaporator and condenser and never get the correct heat transfer from it. The system charge weight is for a vacuumed system, that's at 500 microns or less which takes special tools to measure. If your evaporator or condenser is clogged, you'll never get good numbers because of low airflow/heat transfer. If you're condenser fan isn't pulling enough air you'll never get correct numbers. Your problem sounds like low airflow/heat transfer across the condenser. But it also sounds like you purged your charge to atmosphere and didn't pull a vacuum on it before dumping 3 cans of refrigerant in it. So it's probably overcharged and has moisture/none condensables in it as well.

 

[Matthew Jenkins]

Did you solve this issue? It sounds like the second fan is not turning on or spinning fast enough at idle to pull enough air across the condenser. Spraying water on it will do the same thing. Driving will put air across it. You only need that fan at Idle.