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How can a DEAF or nearly deaf person tell if the AC compressor is running and turning off?


mr. cob
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Howdy All,

A while back I posted about recharging the AC system with one of those do it yourself kits.  Where I live, The Peoples Republik of Washington, such things are now against the law.  Be that as it may, I sourced some of this planet killing, child endangering, stuff and proceeded to install it in my AC system, followed the instructions and am left wondering if I have a compressor problem.

The air coming out of the vents seems a bit cooler but its NOT cold.  Reading the instructions it says to make sure the AC compressor is running.  Problem is with the engine running I honestly can't hear if the AC compressor starts, runs and shuts off when you flip the switch.  I have sat in the cab and watched the tach as I turn the AC switch off and on, I see no difference in RPM, so I am clueless at this point.

Any suggestions you can make will be greatly appreciated, thanks.

Dave

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Use the old screwdriver against the ear, or cheekbone, trick.  You'll be able to tell when it cycles both by the noise of the bearings and by the harsh "klunk" when the clutch engages.  A piece of dowel or broom handle works nearly as well.

I had to recharge a tractor last week, which should hold a bit less than your Pete, and it took two 1 pound cans.

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If you are outside the truck, watch the clutch on the front of the compressor.  If the forward part in front of the belt  is turning, the compressor is running.  Note that the compressor will not run if there is not enough refrigerant in the system to get pressure.  Nor will the system pull in refrigerant because the pressure at the low port is too high when the compressor is not running.

You might need to force it to run to get enough in the system to start the upload.  Remove the two pronged connector on the compressor.  Jumper the pins.  The compressor should engage.  Start filling.  After 30 seconds, remove the jumper and put the connector back on the compressor.  Hopefully, there will be enough refrigerant to get pressure and the compressor will cycle on/off on its own.  Watch the pressure on the can's gauge.  Use this chart  https://rechargeac.com/how-to/ac-system-pressure-chart to see what kind of pressure is good on the LOW side for the ambient air temperature.  Open the truck doors and set the fan and temp to max AC.

If the compressor does not cycle on its own, repeat the jumper routine for a few more seconds.

While filling, rotate the can about 45 degrees side-to-side in the upright position. 

Caution:  I believe you would be using R123A refrigerant.  DO NOT turn the can upside down while filling.  If you do, a liquid slug will pass into the compressor locking it up.  Belts will scream and things will break.  

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1 hour ago, NeverEasy said:

If you are outside the truck, watch the clutch on the front of the compressor.  If the forward part in front of the belt  is turning, the compressor is running.  Note that the compressor will not run if there is not enough refrigerant in the system to get pressure.  Nor will the system pull in refrigerant because the pressure at the low port is too high when the compressor is not running.

You might need to force it to run to get enough in the system to start the upload.  Remove the two pronged connector on the compressor.  Jumper the pins.  The compressor should engage.  Start filling.  After 30 seconds, remove the jumper and put the connector back on the compressor.  Hopefully, there will be enough refrigerant to get pressure and the compressor will cycle on/off on its own.  Watch the pressure on the can's gauge.  Use this chart  https://rechargeac.com/how-to/ac-system-pressure-chart to see what kind of pressure is good on the LOW side for the ambient air temperature.  Open the truck doors and set the fan and temp to max AC.

If the compressor does not cycle on its own, repeat the jumper routine for a few more seconds.

While filling, rotate the can about 45 degrees side-to-side in the upright position. 

Caution:  I believe you would be using R123A refrigerant.  DO NOT turn the can upside down while filling.  If you do, a liquid slug will pass into the compressor locking it up.  Belts will scream and things will break.  

Howdy Chet,

Thanks for your detailed reply.  My truck takes the new style refrigerant, I will try jumping the contacts and see what happens.  I checked all the fuses, cleaned all the replays there are a ton of what I think are circuit breakers but I don't know if they can be pulled or how to check them. 

Dave

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18 hours ago, NeverEasy said:

If you are outside the truck, watch the clutch on the front of the compressor.  If the forward part in front of the belt  is turning, the compressor is running.  Note that the compressor will not run if there is not enough refrigerant in the system to get pressure.  Nor will the system pull in refrigerant because the pressure at the low port is too high when the compressor is not running.

You might need to force it to run to get enough in the system to start the upload.  Remove the two pronged connector on the compressor.  Jumper the pins.  The compressor should engage.  Start filling.  After 30 seconds, remove the jumper and put the connector back on the compressor.  Hopefully, there will be enough refrigerant to get pressure and the compressor will cycle on/off on its own.  Watch the pressure on the can's gauge.  Use this chart  https://rechargeac.com/how-to/ac-system-pressure-chart to see what kind of pressure is good on the LOW side for the ambient air temperature.  Open the truck doors and set the fan and temp to max AC.

If the compressor does not cycle on its own, repeat the jumper routine for a few more seconds.

While filling, rotate the can about 45 degrees side-to-side in the upright position. 

Caution:  I believe you would be using R123A refrigerant.  DO NOT turn the can upside down while filling.  If you do, a liquid slug will pass into the compressor locking it up.  Belts will scream and things will break.  

As NeverEasy says, most truck compressors have a open clutch, and you can visibly tell if the center part of the drive pulley is turning. Most construction/farm equipment and probably a few trucks have a cover over the center section to keep dirt out.

If the compressor is in an open spot, you can also feel the hoses. The low side will be cool, and the high side will be warm/hot if the compressor is running.

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22 hours ago, NeverEasy said:

You might need to force it to run to get enough in the system to start the upload.  Remove the two pronged connector on the compressor.  Jumper the pins.  The compressor should engage.

It you completed the above and the compressor run, my suggestion may help.

I have a factory installed pressure plumbed into the high side that failed, It takes pressure to close the contacts allowing the compressor to run. If you have low freon or a bad switch the compressor would not run. I had a bad switch which is presently jumped out.

Clay 2015 FL M2

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What Glenn West said is a good idea if you have the equipment on hand. Not many do.  And if your system has leaks, your new charge will disappear in short order.   Find a friend!

Your system may already be out of freon if you did not get a can in there before giving up.  Dumping a lot of refrigerant into the atmosphere from a big truck has never been my idea of good protection of the environment.  Take it to a shop and have it evacuated.  Cost me $223 four years ago.  Probably twice that now.

Now I have a full set of hvac maintenance gauges and hoses so I can use it to add freon or air and control it while watching both the low side and high side of the system.  I also bought a nitrogen bottle to air up the truck tires and charge the ac system with dry nitrogen.  More $.  

By dumping the system to the atmosphere, you have exposed the entire system to plan ole air.  No big deal, the vacuum pump will clear it when ready.  Checking for leaks before continuing.  Build a shop air adapter to connect to the low pressure charging port.  Use a regulator to pressurize the system to 100-125 p.s.i.  Get some bubble soap and start spraying all the tubes and connections you can find.  Don't forget the bunk station if so equipped.  Fix leaks, re-test, fix leaks, re-test.  No sense in dumping expensive freon into a leaking system (which you have or you would not be re-charging).  Small leaks can go a couple of years before a need to recharge.

Here is an idea.  Don't dump the system until you have searched for leaks.  Assuming your can of freon has a gauge on it, with the truck off, connect the can to the low pressure port.  Don't pull the can's lever to charge!  Read the pressure.  With the engine off and therefore the ac pump not running, the high pressure side should be dumping pressure to the low pressure side and therefore, if there is any freon in the system it should show something above 45 p.s.i.  If not, the system is almost empty anyway.  Now, don't dump the system, yet.  Make the shop air adapter and with a regulator, bring up the pressure to 100-125 p.s.i.  I used a hose off an old can of refrigerant and inserted a valve in the line between the shop air adapter and the low pressure connector.  That let me air up the system to 125 p.s.i, close the valve, and see if it starts dropping pressure. If it does, do the stuff in the paragraph above. 

 

This is a link to repair to my Volvo system in 2018.  It is still holding.

 

Re-charging it involves having a vacuum pump (a heavy duty one that will run for hours) or there is an air type (inexpensive) that works with a compressor that will work for hours..  At that point, you are probably well ahead to take it to a shop to be done due to the vacuum pump expense.

 

 

Edited by NeverEasy
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You can rent vacuum pump and guages for free from auto parts houses. You pay up front and refunded when returned. I seriously doubt you have any freon in your system by what you posted.  Also my leak was the evaluator core. New shiny core in front of radiator now. 

Edited by GlennWest
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