CompAir Jetair J15 Compressor keeps blowing fuses

[rizla13]

Hi guys,

I have a old CompAir Jetair J15 compressor and has been working for the past 15yrs.

It is connected to single phase 13amp plug.

Recently 8 times out of 10 the fuse blows when the motor kicks in to the replenish the air.

Could this be the motor start capacitor and motor run capacitor issue? Or the motor going faulty?

I have attached the pictures of both caps

Any help apprecated

 

[carbon]

Does this blow a fuse when starting with the reciever empty? If not then check the non return valve that’s fitted into the reciever at the end of the outlet pipe from the pump. Drain all the air first then remove the cap on the valve, if there is any debris between the valve and seat it can mean that the motor is trying to start at full load and blow the fuse that way.

 

[rizla13]

No. When i first start it in the morning it never blows. It’s when it’s trying to re pressure itself it blows. Not always but majority of the time. Id say around 8 times out of 10

 

[rizla13]

I have attached a picture of what I think is the valve. Is this the non return valve circled in red?

do i just remove the top nut? Is that the cap you talking about to clean?

 

[Seadog]

That is the non-return valve. I don't think that that is the issue, though. There should be some sort of unloader valve that releases the pressure in the pipe going to the pump head. Usually as the motor stops you'll hear a hiss for a few seconds as that operates. Generally it's part of the pressure switch. If the NRV is leaking then, provided the unloader is working you will lose pressure in the receiver fairly quickly. As a test just crack open the pipe on the right hand side of the NRV when there is some pressure in the system. If it hisses for a bit and then stops, you've a problem with the unloader, but I'm not sure of the arrangement on this compressor. The Bambi silent compressor uses a machined leakage path on the exhaust reed valve whereas my much older IR compressor uses a mechanical valve which is operated by the pressure switch as the receiver comes up to pressure and the motor is switched off.

 

[the snooper]

Follow the thin black pipe it should go to the unloading valve

 

[rizla13]

Thanks. Is the unloader valve something i can clean a out it back in or doea it have to be replaced?
And is ir better to replace the NRV also?
Also i take it from the sounds of what people are saying it’s not a motor fault?
Thanks

 

[Retired]

Hi,

If this is the first problem in 15 years I'd suspect the capacitors and as it's cap start cap run the centrifugal switch in the motor?

https://circuitglobe.com/capacitor-start-capacitor-run-motor.html

Kind regards, Colin.

 

[the snooper]

Thanks. Is the unloader valve something i can clean a out it back in or doea it have to be replaced?
And is ir better to replace the NRV also?
Also i take it from the sounds of what people are saying it’s not a motor fault?
Thanks

If it doesn't hiss when it cuts out the pressure remains in the delivery pipe making it very hard for the motor to start, you may be able to dismantle the valve depending on type if not they aren't that expensive

 

[the snooper]

Hi,

If this is the first problem in 15 years I'd suspect the capacitors and as it's cap start cap run the centrifugal switch in the motor?

https://circuitglobe.com/capacitor-start-capacitor-run-motor.html

Kind regards, Colin.

It's only happening when the pressure drops not when empty which usually indicates the unloader valve

 

[rizla13]

Is the unloader valve cleanable or just put a new one in?

Where would the underloader valve be located on this?

I have attached a full l picture of the compressor

 

[Retired]

Hi,

When the unloader valve failed on my Hydrovane the pressure ran well into the red before I switched it off it being dangerous.

Good luck; I'll be interested to learn what the problem was.

http://theworkshopcompressor.com/learn/air-compressor-parts/air-compressor-unloader/

Kind regards, Colin.

 

[EBME2]

As The snooper says follow the black plastic pipe from the non return valve, my guess is it will end up at the pressure switch block where you normally pull up a button to switch the compressor on. These are only £20 at machine mart so could be had for less elsewhere. I also agree with the cause, easy to tell just listen out for the hiss when your compressor gets up to pressure and switches off, sounds a bit like a truck air brakes being released. If it doesn’t hiss likely broken.

Might just need to hunt one down with correct connections or be prepared to adapt.

 

[Seadog]

When the unloader valve failed on my Hydrovane the pressure ran well into the red before I switched it off it being dangerous.

That was the pressure switch that failed, not the unloader.

 

[rizla13]

Ok thanks. Will try it

one thing I forgot to mention as now you mentioned it was that it does hiss and loose pressure

 

[Seadog]

As The snooper says follow the black plastic pipe from the non return valve

The cream box with the on/off switch is the pressure switch which incorporates the unloader valve.

 

[rizla13]

Actually the leaking is from the actual hose not the compressor itself but i will double check tomorrow

 

[carbon]

If it constantly leaks rather than stop after a few seconds then possible something in the non return valve as i suggested before.

do i just remove the top nut? Is that the cap you talking about to clean?

Yes with the air drained unscrew the top and check for debris under the rubber pastel.

 

[James1979]

Telling is the one on mine is black and newish looking not white so a good chance it’s been replaced. Wonder if it was unloaded valve and if they are prone?

 

[Retired]

Hi,

That was the pressure switch that failed, not the unloader.

Strange then having sorted the unloader valve out the hydrovane worked perfectly.

Kind regards, Colin.