I need some AC Help please - Ford Powerstroke Diesel Forum
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Old 07-06-2014, 06:52 AM
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I need some AC Help please

My 2k 7.3 ac works great except every now and then when I run the fan wide open it quits cooling and then later starts cooling again. Any ideas what is causing this? Getting ready to make a long run to Islamorada Fla. pulling a boat, so I really need to get this fixed.
I am not a mechanic but mechanically inclined with lots of tools.
Thanks in advance.
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Old 07-06-2014, 07:18 AM
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My 2000 does this occasionally as well. Usually I think it is just my imagination or I am just really hot and it seems to be underperforming but then later it freezes me out of the cab. I am following this as well to see what people say.

I do know that I have read about the clutch shims needing to be removed as the electromagnets that draw the compressor clutch become weak over time and cannot pull the clutch into the compressor unless the gap is minimized. I haven't had a repeated enough problem to necessitate taking the clutch off the compressor and removing shims. Search the forum for clutch shims, ac compressor ect...

Last edited by biscayne; 07-06-2014 at 07:24 AM. Reason: added info as an afterthought.
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Old 07-06-2014, 07:23 AM
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Probably just low on freon. You can get those cans with a gauge at most auto parts stores for the low side and charge it up according to outside temp. It probably won't need much.

After that you should be good to go!



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Old 07-06-2014, 07:29 AM
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Either it's a tad too full of freon (R134a) or your air gap on your compressor could be out of spec.

If it's too full, it will cause an over-pressurization condition (on the high side) and will cause your compressor to unlock. Get a set of AC gauges to check both high side and low side pressures.

If your air gap is out of spec, the clutch won't be able to engage, particularly when it gets hot outside and your clutch and compressor get hot.

Finally, ensure that your cooling fan is performing properly (which is what my situation ended up being). It may seem kind of strange, but it should lock up partially in order to pull air across the condenser and maintain your cold air conditioning.
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Old 07-06-2014, 07:31 AM
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Quote:
Originally Posted by Ricemiester View Post
Probably just low on freon. You can get those cans with a gauge at most auto parts stores for the low side and charge it up according to outside temp. It probably won't need much.

After that you should be good to go!



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Based on freezing cold at some times and then not working at other times, it is unlikely too low. You HAVE to measure both high side and low side pressures. Those cheapy throw away AC cans ONLY measure low side, so it's very easy to over-pressurize the system.
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Old 07-06-2014, 09:11 AM
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If you over pressurize then the low side will also be too high. Pressure of freon isn't only based on the amount in the system. It is also based on temperature of the freon itself. So if your fan clutch isn't working your pressures will rise. If your orifice is clogged your high side will be too high and low side will be low. Even if it does over pressurize it will kick the compressor out and you'll need to tear into the system anyway.

The reason I recommended the charge can was if he had to be "Ballin' on a Budget" was all.


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Old 07-06-2014, 10:06 AM
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Mine the clutch won't engage sometimes so I hop out tap it in, and it gets good and cold but eventually pops back out, so I repeat the process, I've never messed with an a/c system so not really sure what to do about it other then go to a shop, but I hate paying for mechanic work that I should be able to perform in my driveway
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Old 07-06-2014, 12:16 PM
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Quote:
Originally Posted by Ricemiester View Post
If you over pressurize then the low side will also be too high. Pressure of freon isn't only based on the amount in the system. It is also based on temperature of the freon itself. So if your fan clutch isn't working your pressures will rise. If your orifice is clogged your high side will be too high and low side will be low. Even if it does over pressurize it will kick the compressor out and you'll need to tear into the system anyway.

The reason I recommended the charge can was if he had to be "Ballin' on a Budget" was all.


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You mentioned a clogged orifice tube and also air in the system can cause the same issue. Just throwing another can in the system can lead to a VERY bad day... The Harbor Freight gauges are $50, they are the correct tool for the job and can prevent hours of frustration. It's better than just throwing a $30 can of freon at the problem and hoping that you get lucky.
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Old 07-06-2014, 01:43 PM
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When it stops working tap on the front of the A/C clutch and see if it starts cooling again. Mine is doing this. Could be time to remove shims or new clutch.
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Old 07-06-2014, 07:57 PM
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That's exactly what mine does, when I tap it starts spinning again
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