Emglo AM78 HC4V won't run for more than about 5 sec's


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Old 09-25-08, 09:55 AM
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Emglo AM78 HC4V won't run for more than about 5 sec's

Hi, I purchased a used Emglo model AM78 HC4V a couple of days ago. This is my first time w/ an a/c, when I tried it worked fine the 1st time ran up to about 120 psi shut off held air when down to approx. 90 psi cycled back up, Great so i got some tools engine cleaner, 15-50W synthetic oil next day. sprayed cleaner on it, came back hosed off cleaner, ran comp and used new air gun to blow dry(thinking this is going to be cool) started filling up so low car tires then the unit shut down. I used restart and it started for a couple of sec's tried several times seemed to last a few more sec' Took into garage and plugged directly into remembered not supposed to use long extension cords so unplugged (noticed rubber plug housing very hot) ran loner 10sec's and quiter. i disconnected after cooler line from head air coming out but same result. After sitting overnight it run about 15 sec's before shutting off. put air in tank but less than 20psi.
 
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Old 09-25-08, 03:20 PM
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is it tripping the onboard breaker or shutting off at the pressure switch ?
 
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Old 09-25-08, 05:49 PM
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I have the same model, and in addition to help from the friends here, I found this troubleshooting information helpful when I needed to work on mine.
 
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Old 09-25-08, 08:37 PM
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Originally Posted by flopshot View Post
is it tripping the onboard breaker or shutting off at the pressure switch ?
Flopshot, it is tripping the onboard breaker. even w/ the pump disconnected at the cylinder head.
 
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Old 09-25-08, 09:50 PM
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Originally Posted by XSleeper View Post
I have the same model, and in addition to help from the friends here, I found this troubleshooting information helpful when I needed to work on mine.
Thanks for the info. I'm sure I'll be reviewing it many times.
 
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Old 09-25-08, 10:58 PM
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Cool

I disassembled the comp. to some degree, ie. physically separated the pump/motor from the tanks leaving the wiring connected and removing the motor shroud and disconnecting the aircooler pipe at the pump head, It seems everything is working as it should w/ the exception of the motor which gets hot really quick thus tripping the thermal overload switch. So does anyone have any idea why the motor would be running so hot, everything but the cord appears fine?
 
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Old 09-26-08, 03:22 AM
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never had one do that. the heat you talk about,, is that at the motor or the compressor head ?
short of a bad motor it could be a bad breaker i don't know what could be wrong with the motor that would let it run but then get hot. easy parts swaps would be a new breaker or capcitor. the high temp has me stumped since you've disconnected the air output, the unit is not really working hard.
 
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Old 09-26-08, 04:36 AM
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You could check the items listed under "runs hot" in this PDF.
 

Last edited by XSleeper; 09-26-08 at 04:52 AM.
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Old 09-26-08, 06:25 AM
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Hi

It sounds like you may have fried the auxilary motor coil in the "hose down". That's the worst case, and you'll have to toss the unit. The best case, your start capacitor may be shot. Check it, replace if bad and make some air. Good luck.
 
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Old 09-26-08, 06:42 AM
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Originally Posted by flopshot View Post
never had one do that. the heat you talk about,, is that at the motor or the compressor head ?
short of a bad motor it could be a bad breaker i don't know what could be wrong with the motor that would let it run but then get hot. easy parts swaps would be a new breaker or capcitor. the high temp has me stumped since you've disconnected the air output, the unit is not really working hard.
As it is now (partially disassembled) the unit runs for around 15 sec's maybe it is not running hot. I tried it again this A.M. runs same and is still cool after the 12-15 sec. run. Last time after running it many times the pump head was warm to the touch but the motor was too hot to hold a finger on, I don't know that that isn't normal, they do have the protective shroud around the motor for a reason.
 
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Old 09-26-08, 06:49 AM
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Originally Posted by markiz37 View Post
It sounds like you may have fried the auxilary motor coil in the "hose down". That's the worst case, and you'll have to toss the unit. The best case, your start capacitor may be shot. Check it, replace if bad and make some air. Good luck.
Any suggestions on how to check those things?
 
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Old 09-26-08, 12:05 PM
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Here is a pretty good link on checking a capacitor:

http://www.wikihow.com/Check-a-Start-Capacitor

As far as the windings go, just look at them. Are they partially black or discolored from heat? If so, they may be open, grounded or shorted.
 
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Old 09-26-08, 04:25 PM
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Originally Posted by billt1961 View Post
Last time after running it many times the pump head was warm to the touch but the motor was too hot to hold a finger on, I don't know that that isn't normal,



they do have the protective shroud around the motor for a reason.


the comp head will get warm. it's a byproduct of compressing air. the shroud is part of the cooling system and should not be removed.
 
 

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