Wierd A/C problem
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From: Waxahachie, Texas
Wierd A/C problem
I have a wierd problem with my A/C on my 1991 Ford Ranger. When you get in and start driving and crank on the A/c it blows real cold between 38-40 degrees on the thermometer that I stuck in the vent. the problem is after 10-15 mins it will stop blowing cold for about 5-10 then go back to blowing cold. I do not think that it is low on Freon because of how cold it get when it's blowing. When it quits blowing cold for that time period it blows about 70 degrees. Has anybody ever heard of this or seen this problem. It's been 100 down here in Texas and it feels good for 10-15 mins then for 5-10 it does not feel good. Please chime in if you have any info. This system has been retrofitted and up until the past two weeks have had no issues it will get so cold in there you would have to cut it down, not during the 100 degree do though. Is it possible that something is freezing up or some switch somewhere is getting too hot or cold and cutting it off. The fan blows just not cool air have just never seen this before.
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From: Eastern WA
Originally Posted by iracekx
Is it possible that something is freezing up.....
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From: Durham, NC
Originally Posted by Piffery1
Check your refrigerant level. Slightly low will cause the Evaporator to ice up, stop cooling then restart when ice melts.
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From: Eastern WA
Originally Posted by Bob Ayers
If it was evaporator icing, it wouldn't return to cooling properly unless you shut it down and waited awhile. This is the only way the evaporator would defrost.
*In the old days, back when automotive A/C used expansion valves, low suction pressure due to a low charge really would ice the evaporator core over and turn it into a solid block of ice. This was frequently found on aftermarket A/C of the under dash or "custom" in dash variety. In fact, I've seen these units ice over and actually have less than zero psi on the suction side (ie, draw a vacuum). This, as we know, is a really bad deal as now one begins to worry about drawing air into the system.
Last edited by CowboyBilly9Mile; Aug 4, 2006 at 08:55 PM.
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From: Niceville, FL.
CowboyBilly9Mile is correct--I released my mouth clutch pedal before putting my brain in gear! Didn't think enough to realize your post meant the engine continued running and the temperature cycled.
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From: Waxahachie, Texas
Originally Posted by CowboyBilly9Mile
Has the system ever been open to the atmosphere for a prolonged period of time? And if so, was a new dryer installed during the conversion? Because your symptoms are consistent with an orifice tube icing up. During the course of the thing blowing hot air, is the compressor running? And when the problem occurs is there a reduction in airflow at the dash vents (indication of evaporator core being iced over; we can talk about how to address that if it's the case)? Can you replicate the problem in your driveway and with gauges hooked up so we can see what the pressures are when this is happening?
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From: Waxahachie, Texas
Originally Posted by CowboyBilly9Mile
Has the system ever been open to the atmosphere for a prolonged period of time? And if so, was a new dryer installed during the conversion? Because your symptoms are consistent with an orifice tube icing up. During the course of the thing blowing hot air, is the compressor running? And when the problem occurs is there a reduction in airflow at the dash vents (indication of evaporator core being iced over; we can talk about how to address that if it's the case)? Can you replicate the problem in your driveway and with gauges hooked up so we can see what the pressures are when this is happening?
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From: Eastern WA
Originally Posted by iracekx
If the air flow changes it might be a tad never paid much attention to that I just new that it was not blowing cold.
*Over the next few days, perhaps carefully scrutanize airflow at the dash vents before and when this problem is occuring and post; this might resolve a few thoughts.
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From: Waxahachie, Texas
I went and got a refill kit that has gauge with the truck ideling the gauge reads right at the edge of blue right before alert. The needle always shows sytem is full. When you rev the motor the needle goes to the middle of the blue showing that the system is full. I can't get a hold of my buddy that actually has the R-134 gauges. The switch that mounts on the side of the dryer could that be going bad. I would have posted earlier but this thread would not open. This past Sunday coming back from the motorcross track it was raining I would guess it was around 90 degrees and I had a 21 mile trip and it did not give me any problems. I really don't know if the fan is blowing as strong as it did when it was new and I usually don't run accross old rangers to tell how strong theirs blows. If it is the switch on the dryer is bad can it be replaced off the dryer without losing your freon. It has been 6 or 7 years ago when I last messed with this truckI can not remember. I replaced the compressor and the dryer the orifice tube when I converted it over. What would be my problem if the air flow slows down does that mean the fan motor or something that is worse. Thanks for all of your help so far.
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From: Waxahachie, Texas
I ran the A/C today dove a few miles pulled into a parking lot raised the hood and checked to see if the compressor would cut off it never did but the unit was still blowing cold not super cold but of course it was 105 today. That is when I felt the dryer and noticed that it was not super cold. When it does this I am usually on the highway makes it hard to pull off and check.
Last edited by iracekx; Aug 11, 2006 at 08:56 PM. Reason: add more info
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From: Charleston Illinois
My 95 Ranger does this as well.
I don't know for sure why, but my guess would be that the compressor clutch is weak. If I push the clutch in on my truck and allow the engine to slow down to lower RPM's the compressor will engage and make cold air. When running at higher RPM's the compressor just doesn't seem to engage. Like I said before I assume that the compressor clutch is weak or worn out. Since My truck has a manual trans it is easy enough to get it going again.
If your's is automatic you might be able to put it in neutral on the highway to see if the compressor will kick back in. At least you will know that you have the same problem as my truck.
Now about how to fix it? I guess we will have to wait for someone else to answer that. I'm just planning on replacing the compressor clutch on mine.
I don't know for sure why, but my guess would be that the compressor clutch is weak. If I push the clutch in on my truck and allow the engine to slow down to lower RPM's the compressor will engage and make cold air. When running at higher RPM's the compressor just doesn't seem to engage. Like I said before I assume that the compressor clutch is weak or worn out. Since My truck has a manual trans it is easy enough to get it going again.
If your's is automatic you might be able to put it in neutral on the highway to see if the compressor will kick back in. At least you will know that you have the same problem as my truck.
Now about how to fix it? I guess we will have to wait for someone else to answer that. I'm just planning on replacing the compressor clutch on mine.
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From: Waxahachie, Texas
What is the switch that mounts to the dryer actually suppose to do? If it is the clutch does that means new compressor new dryer orfice tube in other words redo the whole entire thing. Is it possible to replace the clutch without taking the system down. I guess this could be some real crappy news.