A/C Manifold Gauge Readings - Do these look OK?

[BTR]

2000 Explorer 4-Door 2WD 4.0L SOHC 140,000 miles. R-134a refrigerant, PAG 46 oil. Do these A/C pressures look OK... or do they indicate something's wrong?

All doors and windows open, parked in the shade, A/C on max (recirculate) and maximum cold, front and rear blowers on high.

85 degrees F ambient - steady 1500 RPM for about 10 minutes - 32 low side - 225 high side.

86 degrees F ambient - at idle (approximately 600 RPM) for about 5 minutes - 45 low side - 215 high side.

87 degrees F ambient - at idle (approximately 600 RPM) for about 8 minutes - 47 low side - 235 high side.

Your thoughts? Thanks.

 

[koda2000]

2000 Explorer 4-Door 2WD 4.0L SOHC 140,000 miles. R-134a refrigerant, PAG 46 oil. Do these A/C pressures look OK... or do they indicate something's wrong?

All doors and windows open, parked in the shade, A/C on max (recirculate) and maximum cold, front and rear blowers on high.

85 degrees F ambient - steady 1500 RPM for about 10 minutes - 32 low side - 225 high side.

86 degrees F ambient - at idle (approximately 600 RPM) for about 5 minutes - 45 low side - 215 high side.

87 degrees F ambient - at idle (approximately 600 RPM) for about 8 minutes - 47 low side - 235 high side.

Your thoughts? Thanks.

AC System Pressure Chart - A/C recharge kits

rechargeac.com

Personally, I find the low side pressures in this chart to be a bit high (indicating overcharged) by 8-10 psi, but the chart should give you an idea of what happens to pressures based on ambient outside temps.

 

[ranger7ltr]

Where did you measure your ambient temp? If the temp was near the condenser core I would say you are in good range of 2.3-2.7x ambient temp for your high side...I would close your windows as the heated air will raise your low side since it is adding heat load to the evaporator as it is trying to cool the recirc air...I would think with these pressures on the high side your bigger a/c is dripping lots of condensate and the smaller line is hotter than heck...Vent temps with the windows closed should be in the mid to high 40's at lower rpm and lower at higher rpm...

What are your vent temps while driving? You should be in the low 40's-mid 30's if you vacuumed the system dry and I believe you did well with the pressures you have especially on the high side...

 

[koda2000]

Where did you measure your ambient temp? If the temp was near the condenser core I would say you are in good range of 2.3-2.7x ambient temp for your high side...I would close your windows as the heated air will raise your low side since it is adding heat load to the evaporator as it is trying to cool the recirc air...I would think with these pressures on the high side your bigger a/c is dripping lots of condensate and the smaller line is hotter than heck...Vent temps with the windows closed should be in the mid to high 40's at lower rpm and lower at higher rpm...

What are your vent temps while driving? You should be in the low 40's-mid 30's if you vacuumed the system dry and I believe you did well with the pressures you have especially on the high side...

Yeah, I didn't get the leaving windows open part either. I've never heard of anyone doing this. I had to add some R134a to the system on my '01 Sport Trac today. My Vent temps driving were around 60 degrees with ambient temps in the low 80's. After adding 12 oz of refrigerant my vent temps are now between 38-45 degrees with ambient temps of 83 degrees. My compressor cycle times were running around 5 seconds, now there back to a more normal 8-9 seconds. I know I have a high pressure line/hose that's leaking compressor oil and obviously refrigerant, but the leak has been there for about 5 years and this is the first time I've had to add refrigerant. If it keeps working through this summer after just adding some refrigerant it's good enough. I'd rather add $3-$4 worth of R134a than have to evacuate the system, buy a new high pressure line/hose, install it, pull a vacuum on the system, replace the accumulator/drier and refill the system. Next week I'm going to also put in a 3 oz PAG 46 oil charge to make up for the compressor oil that's leaked out.

 

[BTR]

@ranger7ltr,

Where did you measure your ambient temp? I measured ambient temp in the passenger-side foot well... at the carpet. Truck was in the shade; all doors and windows open; vents aimed away from foot well.

What are your vent temps while driving? You should be in the low 40's-mid 30's if you vacuumed the system dry and I believe you did well with the pressures you have especially on the high side. I haven't measured the vent temps yet. TBD.

 

[BTR]

@koda2000,

It’s odd. Finding the charge chart wasn’t difficult. However, finding the procedure is, basically, impossible. I found online content that said to do it with the doors and windows open, and I also found content that said the exact opposite. I found content that said to measure the ambient in the foot well, anywhere outside the vehicle, and in front of the condenser. I’m very particular about charging exactly to the chart, but it’s difficult because I don’t know --- for sure --- what procedures to use.

Like you, my high-side hose was leaking. I decided to bite the bullet and replace then manifold hose assembly. This repair required me to pump-down the system. One good thing about pumping it down is that I --- for sure --- now know that it contains exactly 30 oz of R-134a.

Since I didn’t flush the system, the most difficult decision I had to make (guesstimate) was how much PAG 46 oil to add.

 

[ranger7ltr]

Check out ackits.com for lots of a/c stuff...I learned from a genius mechanic decades ago first with R-12 then with R134a to understand the properties of AC and what to look for.
Anyway I have always measured ambient at the front of the condenser with the doors and windows closed and the fan speed mid cycle...The airflow through the radiator and condenser baseline the pressures as you charge since as you drive the ram air effect will help to increase the heat transfer from the superheated vapor in the condenser and help absorb more heat into the cooled liquid flowing through the evaporator...

I too "top off" my Explorer ac system once a year or two as the vent temps increase...I still use the 2.3-2.7x ambient for the high side pressures to stop adding refrigerant and it get down to 37-45F until I need to add more again...I am not leaking oil that I can see and the minor leak is coming from the compressor seal but I am not losing enough to change the compressor or the seal...

The amount of oil in the system is obviously critcal...Too little oil and the compressor eats itself too much oil and the cooling is affected and can hydraulic itself dead...I believe the system measurement is 30 oz of oil but this is coming from memory which I question... I would verify that and resist the urge to add a little more...The main oil locations are the condenser, accumulator and hoses...If you used compressed air to blow them out and replaced the accumulator you got all or most of the oil out of the system...

 

[BTR]

@ranger7ltr - Very helpful! Thanks! A few more questions:

1. Do you park in the shade? Yes? No?
2. Are both blowers (fans) on, or just the blower for the front seats? My 2000 Explorer has one evaporator and two blowers (one for front seats; one for back seats). Both? Only the front?
3. Is/are the blower/blowers on medium, or on high? Which speed?
4. Is the engine at idle (about 700 RPMs with the A/C engaged), or at 1500 RPMs? Which RPMs?

Thanks for your help.

 

[koda2000]

Check out ackits.com for lots of a/c stuff...I learned from a genius mechanic decades ago first with R-12 then with R134a to understand the properties of AC and what to look for.
Anyway I have always measured ambient at the front of the condenser with the doors and windows closed and the fan speed mid cycle...The airflow through the radiator and condenser baseline the pressures as you charge since as you drive the ram air effect will help to increase the heat transfer from the superheated vapor in the condenser and help absorb more heat into the cooled liquid flowing through the evaporator...

I too "top off" my Explorer ac system once a year or two as the vent temps increase...I still use the 2.3-2.7x ambient for the high side pressures to stop adding refrigerant and it get down to 37-45F until I need to add more again...I am not leaking oil that I can see and the minor leak is coming from the compressor seal but I am not losing enough to change the compressor or the seal...

The amount of oil in the system is obviously critcal...Too little oil and the compressor eats itself too much oil and the cooling is affected and can hydraulic itself dead...I believe the system measurement is 30 oz of oil but this is coming from memory which I question... I would verify that and resist the urge to add a little more...The main oil locations are the condenser, accumulator and hoses...If you used compressed air to blow them out and replaced the accumulator you got all or most of the oil out of the system...

I show my refrigerant capacity is 30 ounces, but the oil capacity is only 9 ounces of PAG 46. Without replacing the compressor and accumulator/drier there's no way to know how much oil is currently in your system. I'm taking a guess that I'm 2-3 ounces low on oil based on my wet high pressure hose. Without completely evacuating your system there's no way to know exactly how much refrigerant to add (other than by manifold gauge readings).

I didn't realize how much compressor oil I had leaked until I removed my engine and saw the condition of my high pressure hose. This is the first time I've had to add refrigerant in 5 years of ownership, but I did find that there was UV dye in my system.

 

[Gary Crist]

Back in the "dark ages" of R-12 when I was Ford Certified (beta max days),
when doing a system performance test, RPM 2500, max or recirc, fan on high
windows up,doors closedand thermometer in center register,
we looked for 40 degrees.
The Lincolns we could adjust a temp switch under the passenger's side down
to 35-38 degrees.

With a low evap temp, it works great in AZ but freezes up in Houston hence
40 degrees. Ford had to relearn it's lesson again with the 2003 Expys and such
when they eliminated temp control on max. It was cold as a freezer till it
would freeze up here in Dallas!

During an owner's meeting with Ford engineers (my guy was on the 9 3/4 diff team) I
explained how it was not so much the cold we wanted but, the de-humidification! He was
from Detroit or "up there". It was a shock to all of them.

 

[BTR]

@koda2000 - I found a bona fide Ford A/C document. It includes the procedure, charge charts, a vent temp chart, and compressor cycling charts. It also includes an EXCELLENT (and extensive) table for diagnosing almost any problem based on the measurements from the charts. I'm not sure it will attach here, so feel free to hit me up via a conversation (or whatever it's called in this forum) and I'll get it to you.

 

[BTR]

NEW MEASUREMENTS - THESE MEASUREMENTS WERE GATHERED USING THE PROCEDURE OUTLINED IN THE FORD DOCUMENT

89F - Ambient temp in front of condenser.
41F - Middle vent temp. Ford chart states a range of 38-49.
23/205 PSI - Low/high at 10 minutes. Ford chart states ranges of 21-52 and 182-275.

It looks like my evacuating, oiling, and charging were done properly. Mission accomplished.

 

[ranger7ltr]

High side pressure looks good 2.3x ambient temp...Low side in good range no clogs in the system... Vent temps look good and your compressor will like you for oiling it right, getting the system dry as possible and charging it right...You did well!!!

Congrats on the nice vent temps as well...I am certain you will enjoy them during this hot summer...

 

[koda2000]

@koda2000 - I found a bona fide Ford A/C document. It includes the procedure, charge charts, a vent temp chart, and compressor cycling charts. It also includes an EXCELLENT (and extensive) table for diagnosing almost any problem based on the measurements from the charts. I'm not sure it will attach here, so feel free to hit me up via a conversation (or whatever it's called in this forum) and I'll get it to you.

I wouldn't mind having the Ford A/C info to add to my collection. Is this something you found on-line? If so, can you provide a link to it?

 

[BTR]

I wouldn't mind having the Ford A/C info to add to my collection. Is this something you found on-line? If so, can you provide a link to it?

I don't recall where I found it. Sorry. I have it as a PDF. Send me a message and I'll reply.

 

[BTR]

AC System Pressure Chart - A/C recharge kits

rechargeac.com

Personally, I find the low-side pressures in this chart to be a bit high (indicating overcharged) by 8-10 psi, but the chart should give you an idea of what happens to pressures based on ambient outside temps.

@koda2000 - You're correct (in saying that the low-side pressures in the "generic" R-134a chart seem high)! Assuming the generic chart and the Ford chart both use the same procedure for gathering pressure and temperature readings (which can't be assumed because the generic chart doesn't outline the procedure), then the generic chart does in fact call for much higher low-side pressures. At 90F ambient, the charts call for:

Generic R-134a Chart
45-55 low side. 250-270 high side.

Ford Chart
22-52 low side. 188-278 high side.

 

[koda2000]

@koda2000 - You're correct (in saying that the low-side pressures in the "generic" R-134a chart seem high)! Assuming the generic chart and the Ford chart both use the same procedure for gathering pressure and temperature readings (which can't be assumed because the generic chart doesn't outline the procedure), then the generic chart does in fact call for much higher low-side pressures. At 90F ambient, the charts call for:

Generic R-134a Chart
45-55 low side. 250-270 high side.

Ford Chart
22-52 low side. 188-278 high side.

Yeah the Ford chart is the range I'm now in. In the mid 20's low side and 250's on the high side. I don't recall the outside temp when I took them. I think it was around 80 degrees. Mine;s nice and cold now. Today it was around 84 degrees out and my vent tents were running high 30's to mid 40's. I picked up a can of 3 ounce can of PAG 46 oil charge today and a scale. I going to put in an ounce and a half of oil as I know I've lost some. I'm curious to see how long mine stays cold. I'm hoping for at least until the end of summer. May next spring I'll replace my leaky high pressure line assembly.

BTW, fordtechmakuloco has a 5-part series on A/C that's interesting to watch, though not all the videos are applicable to our vehicles/Fords. Still, they're interesting to watch.