96 Ranger ALWAYS blows HOT/fast cycling AC

[Greg 713]

I got a "new to me" 2.3 Ranger and I am getting all of the little issues resolved. I bought it to resell but dog gone it I LIKE the truck. A LOT! So it might very well be a keeper.

So I read many of the threads about heating and AC. Great bit of information on this site. When my brother had his Ranger this was the go to site for him.

OK, so the air coming out of the vent, heat, blend (heat+defrost) or defrost is HOT. When I run the A/C it cycles quickly. Following is the information that will help you super star Ranger mechanics figure this out!

-Blend door has been replaced (previous to me owning it).
-Heater control valve works with external vacuum (verified by taking it off and looking at butterfly valve).
-Compressor will fast cycle with the low pressure AND high pressure switiches jumped at the same time.
-Compressor runs (short cycles) on Max AC, AC, heat and defrost but not on vent (as it should).
-No vacuum at the heater control valve while running. If I take the vacuum line off several hours AFTER running the line will have vacuum.
-As mentioned the a/c vent, heat, blend and defrost work it is just always HOT.

I ordered a temperature switch and that will be here Monday. I arrived at this possible conclusion because several places the site mentions the control switch is a weak spot. Here is where I need help, does the following lead you to think temp switch?
-With the compressor high/low sides jumped the only other switch is the temp control*.
-Not a blend door because the other HVAC functions operate properly.
-The heater control valve operates properly with external vacuum.
-Last and MOST importantly I want it to be the switch because it has been ordered and it is cheap!!

* I read IAC will cycle the compressor if dirty. Reading more about that. But it cycled with about 2000+ RPMs

Thanks in advance for your help.

 

[Greg 713]

Well the temp control/potentiometer made no difference. What is left?

 

[Greg 713]

I took the blend door actuator off and it does not move. How do you test the leads to make sure it is getting power and the actuator is indeed bad. I don't want to buy another part only to find the problem is elsewhere. The blend door is OK. The top of the "pivot" is not broken.

 

[97RangerXLT]

You are low on refrigerant. That is why you had to jump the pressure switch to get the compressor to cycle. The low side pressure switch is there to save your compressor from trashing itself due to no lubrication (because the refrigerant is what caries the oil).

You will need to add some oil and refrigerant. Your best bet is to take it to a shop and have them put the correct amount in as they have equipment that can measure how much is needed and how much is already in there. You can also charge it yourself with a full manifold gage set and a temperature pressure chart, but you will take the chance of overcharging it.

Also put a leak detecting dye in it to find where the refrigerant is leaking. On the top of your radiator support there should be a sticker with the max refrigerant capacity. DO NOT EXCEED THAT AMOUNT!

AJ

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[cvar]

+1
Your refrigerant is low, most likely, which is usually due to leaking O-rings.
The other likely possibility is your Orifice-Tube is plugged.
See Ford service charts in http://imgur.com/a/xMUKH

 

[Greg 713]

You are low on refrigerant. That is why you had to jump the pressure switch to get the compressor to cycle.

I jumped the low and high side TOGETHER and it still cycled. First I jumped the low side with no change. Then I jumped the high side with no change and then I jumped both with no change. This is what lead me to think the temp control switch or the IAC valve.

Even with a gauge it is hard to tell what the pressure is in the system because it cycles so often.

+1
Your refrigerant is low, most likely, which is usually due to leaking O-rings.
The other likely possibility is your Orifice-Tube is plugged.
See Ford service charts in http://imgur.com/a/xMUKH

Wouldn't jumping the high side limit switch cause it to keep running?
I am seeing how an obstruction might be part of the cycling problem. But when it cycles I do get a little bit of cool air out of the ducts?

Please don't take this as being a braggart but I am not too bad with HVAC so this thing has me stumped. :-(

Maybe I am using the wrong tools. Should I break out the torch?!

Oh, and does anybody have a hint where I might find out what the wires are in the blend door actuator plug so I can see if I have power or if the actuator is bad?

 

[97RangerXLT]

A clutch that cycles frequently is another classic sign of low refrigerant. As you fill it, your compressor will run longer and longer as it gets close to full.

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[97RangerXLT]

Put a manifold gage set on it and take down the readings for both high side and low side. Also take the reading for the temperature outside.



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[97RangerXLT]

Also before you run the compressor, take a static reading of the system. You should have over 70psi on both high and low side. Both gauges should have the same pressure. Also when you turn on the system make sure it is on max ac and the blower is on full

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[Greg 713]

Blend door actuator follow-up. I took the "box" apart and put leads directly to the motor and the motor ran without issue. I cleaned the contacts and put a lite coat of dielectric grease on the slide area. I put the box back together and hooked it up to the harness then turned the temp control. The actuator did nothing.

I do have power to the actuator (can't remember the wire color) but one pin is hot with the key on.







fyi-it is a LIGHT coat, it just looks like it is on there thicker than peanut butter.

 

[Greg 713]

A clutch that cycles frequently is another classic sign of low refrigerant. As you fill it, your compressor will run longer and longer as it gets close to full.

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Why would it cycle if I have both the low side and high side limit switches jumped at the same time. In theory it should run continuously. Why is it still cycling.

It might be I have two separate issues. What about the HVAC computer, is that a problem area?

 

[4x4junkie]

Unless there's something different about the A/C on a '96 vs my '90 & '94, jumping the low-side pressure switch should indeed be all that's necessary to cause the comp to run continuous.

Is it possible whatever you jumped it with failed to make contact? (leaving the switch to still cycle)?

(that is, unless you pulled the connector off the switch completely and stuck a jumper in that, in which case it would either run constant, or not at all, which I don't have an answer for why it still cycling)

 

[97RangerXLT]

^^ what he said.

Another thing to look at, is your clutch coil going bad? that could also cause intermittent cycling even with the switch jumpered. that is the only thing that I can think of. that you have an intermittent contact in the a/c clutch coil.

something else that I learned on my Ranger. when you start it up and the motor is cold, but it is blustery hot outside, the a/c will run for a min or two and then the clutch cuts out. once you get moving and air goes across the condenser, the clutch kicks back in again.

the thing that I figured is happening is that the pressure is building up because of the heat (thermodynamics...) causing the high pressure switch to open. once the airflow goes across the condenser and cools things down, the pressure drops and the high pressure switch closes and the a/c compressor kicks in again.

This is not a problem once the motor is warm and the mechanical fan clutch kicks in.

Just an observation.

AJ

 

[Greg 713]

(that is, unless you pulled the connector off the switch completely and stuck a jumper in that, in which case it would either run constant, or not at all, which I don't have an answer for why it still cycling)

That is what I did, pulled the connector off and jumped across the plug end and it is no loose.

something else that I learned on my Ranger. when you start it up and the motor is cold, but it is blustery hot outside, the a/c will run for a min or two and then the clutch cuts out. once you get moving and air goes across the condenser, the clutch kicks back in again.

I will give this a try. I have been doing all of this in the driveway because the truck isn't licensed. But I might take it out on a backroad and see if driving at 45+ MPH makes it run normal.

Still stumped on why I don't have vacuum to the heater bypass valve. Fixing the clutch master slave and clutch was the EASY part! Sheesh! this HVAC is kicking my butt.

 

[Greg 713]

Quick update. The blend door actuator was bad. The blend door might have been replaced but guess what, it is still broken.

So going back to the most common problem, the blend door followed by another common issue the blend door actuator. I have the actuator but I have to order and replace the blend door.

Did not have a chance to see if the bad actuator caused the quick recycle or if driving solved the quick recycle. I will get the blend door issue resolved and move on the the fast cycling compressor.

More updates to follow.