This is all generally true but, in my experience, these trucks convert quite well. Vent temps in the high 30's are not uncommon if it is done correctly and a new Motorcraft fan clutch is installed. A parallel flow condenser and auxillary fan will benefit many vehicles, but 80s-90s Ford trucks generally don't need these measures as long as the cooling system is up to par and the engine is basically stock..
Fox Chassis vehicles (Mustang, Capri, Mark VII) are a whole different ballgame.
Peter94, don't even consider the Flex-a-Lite. Replace the existing fan clutch.

 

I was going to replace the fan clutch either way. But I was wondering if adding the flex-a-lite as an auxilary pusher fan in front of the grilll, and wiring it so it would only come on with the a/c, would give me lower vent temps. That is my next question anyway...

 

Hello Peter;

Yes, to a certain extent, the more airflow across the condensor, the cooler the refrigerent. However, don't forget that you have a metering device, either a TXV or FOT that limits how much refrigerent is allowed into the evaporator. That is what controls the A/C's ability to cool, and of course the outlet temp. For the most part, the only time a fan will help much with cooling is at idle or slow speeds, when there isn't enough ram air to cool the engine or to condense the refrigerent into a liquid. Ram air will provide most of the air necessary for proper cooling of the vehicle and A/C while travelling down the highway at 70-80 MPH.

On the other hand, if you get the engine too cool, then it can slip back into open loop operation and cause the cat to plug or the engine to run rich.

Hope that helps some,

Dan Harriman 84 F150 lwb
Orange, Texas

 

Peter;

I just checked on All-Data to see how your girlfriend's sister's Neon A/C works. There is a low-pressure cutoff switch located on the bottom of the H-block. A quick way to see if that switch is good is to disconnect it and jumper it across. With the engine running, the A/C clutch should engage. First, I would check to see if there was 12V to the switch. If there is, then jumper across it. If the clutch still doesn't come on, then check to see if there is 12V at the compressor clutch. If there is, then jumper across the ground side of the connector to the battery and see if it engages.

If the switches are jumpered, there is nothing to control the compressor if the system is low on refrigerent. However, you said that the static pressure is about 110PSI, so that should be about the correct charge. I did notice on All-Data that the system is computer controlled, so if you don't see 12V at the low pressure cut-off switch, then you need to backtrack into the passenger area, including the multifunction switch and the A/C control head.

By the way, there are at least 2 fuses and also an A/C relay in that system.

Good luck,

Dan Harriman 84 F150 lwb
Orange, Texas

 

I too read a lot of good posts. I would like to add a couple of things. FIRST checking evaporator temps on MAX isn't the best. WHY you are drawing inside air, which is as a rule hotter. You want to check it on LOW or NO FAN, on A/C, with engine RPM about 1500-2000. SECOND if you have an A/T COOLER & an ENGINE OIL COOLER in front of your radiator R134A may not work very well. NOT ENOUGH AIR FLOW. If you remove the R134A & replace it with R414B you may find better performance. NOTE R414B requires a LICENSED TECH TO BUY. R414B will mix with any oil. Will mix with R134A or R12.
THIRD, evaporator temps will vary with ambient temps, humidity, dew points, etc. Right now my R-12 sitting in the driveway won't pull down below 50 degrees, as soon as I drive it on the open highway it drops to 34 degrees. The temps here are in the 110s.

 

All good points, except:
R414b contains isobutane and is, thus, illegal to use in an MVAC system in the US. It's also a blend of 3 different gasses, so fractionation is a huge issue if there is a small leak. A leak will allow the lighter, oil carrying components leak out first and can starve the compressor for oil. The system must be leak free and you cannot "top off" when using a blend because of this.
Insurance companies are now aware of hydrocarbon blends and are starting to look for them in vehicles when claims are filed. (You are technically operating the vehicle in an illegal manner, claim rejected).
It is also illegal to mix refrigerants in a system, so you can't legally mix it with R12 or R134a.
R414B also contains R-22. R22 is not campatable with the rubber used in most MVAC systems (contrary to what the mfgr claims).
Use of anything except R-12 or R-134a will void the warranty on AC parts from most manufacturers.
R-12 is still readily available, and the price continues to drop with demand. R-134a works well on most converted systems if the conversion is done properly. There is really no sound reason to use anything else in an MVAC system.

 

I used that stuff once, smells just like propane. A front end collision and BOOOOM!!!
As for the FOX bodies not converting well, that is wrong. My 88 5.0 Mustang has 38 degree air from 134A with no componants replaced as does our 90 MarkVII. Did them both myself.

 

I don't believe that you can get too much airflow and idling around town is the only place that pusher fan is going to help. And it is the only place you need it to work. As far as getting the engine too cool, if the engine gets too cool then you have a major problem with your thermostat.

 

Yes, I concur. It should then be replaced.

Dan Harriman 84 F150 lwb
Orange, Texas

 

"I used that stuff once, smells just like propane. A front end collision and BOOOOM!!!"

Not necessarily a front end collision, but evaporator leaks are a real concern. R414b is somewhat flammible. There are others that are far worse. An evaporator leak could cause the concentration in the passenger compartment to become explosive. One arc at a switch, and ... Propane, butane, etc are excellent refrigerants, but not for systems as we know them currently. That smell is added to get your attention, those gases are actually odorless. It works, don't it?

"As for the FOX bodies not converting well, that is wrong. My 88 5.0 Mustang has 38 degree air from 134A with no componants replaced as does our 90 MarkVII. Did them both myself."


Really?? Fox Mustangs have earned the reputation of being horrible for R134a conversion, due to poor airflow and small condensers. (The condensers used in Fox chassis Fords were margainal to begin with). They cool very well except at idle and low speeds. Their other Fox chassis bretheren convert somewhat better. The airflow to the condenser is a bit better, so the loss at idle isn't quite as bad. My 84 Mark VII does great, but after about 10 minutes in slow traffic on a bright sunny 90+ day, the AC starts wheezing out.
Sun Load is a big problem with the Fox cars. I've had Black\Black Fox Mustangs that wouldn't get under 45 degree outlet temps on the highway on a bright 90+ day. The system just isn't quite up to absorbing the intense heat coming in through the windows. With some clouds or shade, they do ok.

Hey LxMan1! Wanna sell that 90 Mark VII? My 84 is getting really tired and I'm looking for a replacement. I want an 87-92 LSC. (or GTC )The very few I find here in Northern Ohio are rusty and overpriced. I'm on the lookout for a decent one.

 

The early ford trucks (70's) with dealer air suck. This is what I was referring to as needing the new parallel flow condensers.

Different year vehicles have different needs so you can't just categorize all vehicles in the same way. My wifes 86 Bird w/3.8L V6 blows so cold that after 10 minutes in the vehicle you are begging to turn the darn thing down. Our neighbors Mark VII is just the opposite.

 

"The early ford trucks (70's) with dealer air suck. This is what I was referring to as needing the new parallel flow condensers".

You got that right. They needed a turbine fan across the condenser. My 72 Ranger XLT cooled great unless the sun was shining brightly on a hot day. (Red w/red interior, in northern Ohio). The condensrs were puny. The 73-79s are pretty robust and convert pretty well . Much better if you adjust the POA valve to bring the suction side down into the high 20s. The 80-93s(?) convert very well with no mods.

"Different year vehicles have different needs so you can't just categorize all vehicles in the same way. My wifes 86 Bird w/3.8L V6 blows so cold that after 10 minutes in the vehicle you are begging to turn the darn thing down. Our neighbors Mark VII is just the opposite".

Correct, but in general, Fox chassis cars have problems cooling at idle and low speeds after conversion. They all take the same marginal condenser and smallish evaporator. It was barely efficient enough with R-12 in many cases.
When converted to R134a, semantics could push Fox vehicles over the edge of not cooling at low speeds or at idle. Interior and exterior color have a lot to do with it, as does your location and temperature extremes.
The Mustangs are the worst due to the design of the "nose". It tends to block airflow. Most bring complaints after conversion, regardless of color or location. The T-Birds are slightly better, but dark colors kill them at idle. Cougars usually have better airflow (bigger grille), but are more common in darker colors. Mark VIIs have better airflow to the condenser and the lighter color ones convert quite well. The dark ones (like my dark Blue 84) eventually wheeze out at idle on really hot sunny days, while in traffic. The Black and Red LSC SE's with black interior should be left as R12 systems. They will not overcome the sun load on a hot sunny 90+ day with R-134a.

Remember, I'm speaking as someone who charges money to do AC repair (and R134a conversions). If you DIY it, you may not be concerned with a bit less cooling at idle. If you just paid good money to have it done, you're going to critique it closer. If you just paid ~$800-900 to have the AC fixed (and converted to R134) on your Black on Black 89 Mustang GT or T-Bird SuperCoupe, and you get uncomfortable in traffic, are you going to be happy?
That's why I don't convert Fox chassis Ford products to R-134a, as a rule.

 

Hello, my follow up to a past post...
I have a 94 f150 5.0l
I replace fan clutch as lsr told me in past post to cure warmer idle temps...
I clean/sprayed the condenser clean
Installed new orfice/vacuumed
Low side was 29 and high side was 250
I still get warmer temps at idle(w/slight gas 1500rpm) about 58deg.
When crusin around...it takes a while but temps will cool down.
The compressor constantly stays on...never turns off
Any ideas? Thanx

 

It sounds like maybe the cycling switch is stuck closed. Could be the evaporator is freezing over at lower speeds. The switch is screwed onto the side of the accumulator "can" back by the passenger firewall. See if the evaporator lines going into the firewall are frosted.
What is your ambient temperature? Your pressures are about right for 85-90 degrees.

 

Weird you say cycling switch....i just replaced that today cause it was messed up and would not turn on compressor. I would have to fiddle with plug and tap switch to make it turn on compressor...but that is fixed compressor stays on...no frosties...temp about 90 to 95 around here