Brisk air not cooling

[mx842]

I've started to work on my trailer again after I had stopped awhile back because of the hot weather. I have a Brisk air 13,500 BTU unit and the model number is 57915.622. I have searched the net until I am blue in the face and I can't seem to find a service manual for it. I did find an installation manual but it is not much help with trouble shooting.

My problem is that it is not blowing cold air. The fan works on all speeds and it sounds like the compressor is running but I can't really say for sure. I put my amp probe on the hot wire and when I cut the fan on I can see on the meter that it is using around 2.5 to 3 amps. When I turn the thermostat knob up to the cool position the meter jumps up to around 12 amps but it drops right back down to 3 amps. It seems to me that it sounds as if the compressor is doing something but from the looks of the amp draw it is not.

What am I missing here?

[RV Wizard]

With the power off, remove the shroud, open the control box and check the compressor start capactior and PTCR connected to it. It sounds like the controls are energizing the compressor but it is having a hard time starting and cutting out on the thermal overload protector.

[mx842]

Quote:

Originally Posted by RV Wizard With the power off, remove the shroud, open the control box and check the compressor start capactior and PTCR connected to it. It sounds like the controls are energizing the compressor but it is having a hard time starting and cutting out on the thermal overload protector.

This box is on the roof, is that correct? Also what am I checking? is there a test or something I should be looking for?

[Hitchhiker]

If it's the PTCR and start capacitor, this kit on eBay may fix it for you.

[mx842]

Quote:

Originally Posted by RV Wizard With the power off, remove the shroud, open the control box and check the compressor start capactior and PTCR connected to it. It sounds like the controls are energizing the compressor but it is having a hard time starting and cutting out on the thermal overload protector.

I went up there and attempted to check it. I didn't see anything that looked bad, (burned) and I am not sure how to test it. The start and run cap seem to test right but I'm not exactly sure what I should be looking at. What should the PTCR test like. I am guessing this is the small 1" square object that plugs into the start cap and the red wire hooks to.

[mx842]

Quote:

Originally Posted by Hitchhiker If it's the PTCR and start capacitor, this kit on eBay may fix it for you.

I'm not sure if this is bad or not but I bought one just for the heck of it. Thanks for the link.

[Hitchhiker]

Quote:

What should the PTCR test like. I am guessing this is the small 1" square object that plugs into the start cap and the red wire hooks to.

I copied and pasted this from another forum, maybe it'll help:

• A positive temperature coefficient resistor (PTCR) is a resistor that varies its resistance with its temperature. A resistor that changes its resistance characteristics as a function of its temperature is also called a thermistor. So the PTCR is technically a thermistor. PTCRs have been used in the HVAC industry for many years. They are made from a very pure semi conducting ceramic material. Because the PTCR has a positive temperature coefficient, resistance is very low over a wide range of low temperatures. However, when reaching higher temperatures, the resistance increases. These characteristics can be used when starting certain motors. Many times, PTCR devices are used in place of potential or current-type starting relays. PTCRs can provide starting torque in permanent split capacitance (PSC) motors, when the condensing and evaporating pressures have been equalized somewhat during the off cycle.The main advantage of this device is that it has no contacts, coils, or moving parts, thus requiring less maintenance. Also, it is simpler to troubleshoot.

[mx842]

Quote:

Originally Posted by Hitchhiker I copied and pasted this from another forum, maybe it'll help: A positive temperature coefficient resistor (PTCR) is a resistor that varies its resistance with its temperature. A resistor that changes its resistance characteristics as a function of its temperature is also called a thermistor. So the PTCR is technically a thermistor. PTCRs have been used in the HVAC industry for many years. They are made from a very pure semi conducting ceramic material. Because the PTCR has a positive temperature coefficient, resistance is very low over a wide range of low temperatures. However, when reaching higher temperatures, the resistance increases. These characteristics can be used when starting certain motors. Many times, PTCR devices are used in place of potential or current-type starting relays. PTCRs can provide starting torque in permanent split capacitance (PSC) motors, when the condensing and evaporating pressures have been equalized somewhat during the off cycle.The main advantage of this device is that it has no contacts, coils, or moving parts, thus requiring less maintenance. Also, it is simpler to troubleshoot.

It probably would if I knew how to troubleshoot it. Did the forum say anything about that?

[RV Wizard]

Quote:

Originally Posted by mx842 I went up there and attempted to check it. I didn't see anything that looked bad, (burned) and I am not sure how to test it. The start and run cap seem to test right but I'm not exactly sure what I should be looking at. What should the PTCR test like. I am guessing this is the small 1" square object that plugs into the start cap and the red wire hooks to.

Do you have access to a clamp on AC amperage meter? If so you should be able to view the starting amperage of the compressor by clamping an amp meter around the common lead of the compressor and have someone turn it on for you as you watch the meter. To test the capacitors a capacitor tester is a great tool to have but can be checked some by using an ohm meter. With the capacitor removed from the circuit, a rise and fall of resistance will be seen on the ohm meter when connected across the terminals. One other area to inspect is the compressor terminals under the black Bakelite cover on the compressor itself. Verify all wiring connections are good and let us know what you find for amperage at start up and just after.

[mx842]

Quote:

Originally Posted by RV Wizard Do you have access to a clamp on AC amperage meter? If so you should be able to view the starting amperage of the compressor by clamping an amp meter around the common lead of the compressor and have someone turn it on for you as you watch the meter. To test the capacitors a capacitor tester is a great tool to have but can be checked some by using an ohm meter. With the capacitor removed from the circuit, a rise and fall of resistance will be seen on the ohm meter when connected across the terminals. One other area to inspect is the compressor terminals under the black Bakelite cover on the compressor itself. Verify all wiring connections are good and let us know what you find for amperage at start up and just after.

Yes I have an Amprobe RS3 model. It is a clamp on and can check amp draw, voltage up to 600 volts as well as Resistance. I use my Simpsom 260 to defuse the charge that may be left on the capacitor and to test.

Last night before it got dark I took that cover off the wiring on top of the compressor and inspected the terminals and wires going to the compressor and saw nothing that looked unusual. I guess I'll have to wait until this evening when my wife gets home to turn it on for me while I check it. hopefully she gets home tonight before it gets dark.

[mx842]

Quote:

Originally Posted by RV Wizard Do you have access to a clamp on AC amperage meter? If so you should be able to view the starting amperage of the compressor by clamping an amp meter around the common lead of the compressor and have someone turn it on for you as you watch the meter. To test the capacitors a capacitor tester is a great tool to have but can be checked some by using an ohm meter. With the capacitor removed from the circuit, a rise and fall of resistance will be seen on the ohm meter when connected across the terminals. One other area to inspect is the compressor terminals under the black Bakelite cover on the compressor itself. Verify all wiring connections are good and let us know what you find for amperage at start up and just after.

Okay, here is the deal. When I got home I wentup on the roof and got all my stuff together. I have a heavy cord I am using right now that I put a 30 amp plug on so I can plug my shore power cable into the trailer and then plug this other cord into the shore power cable. that way I didn't have to wait for my bride to get home I just turned on the AC unit to full cool and when I want to test I just plug the two cords together.

Here is what I found. On the blue wire to the compressor it goes into the overload switch and out as a black wire and it goes to the common lug. On start up the meter pegs on the 15 amp scale so I switched to the next scale of 0 to 40, the needle shoots up to right at 25 amps then I hear a click and it drops off. I'm thinking it is the overload switch.

The white or run wire is the same jumps up to around 25 and then drops back off to around 2 amps.

I was thinking that the compressor motor may be either bad or locked so I checked the resistance on the terminals going into the compressor and they were as follows.......Between start and run was right at 5000 ohms.
Between start and common was 4700 ohms and from common to run was 300 ohms. There was no reading at all (No continuity ) on any of the terms to ground. The book didn't give what the resistance should be but from the way I read it the compressor test ok.

The voltage at the compressor terminals are as follows.....With the unit on and running there was 280 volts between the start and run terms, between run and common there was 108 volts.....about the same as the voltage was when the compressor was trying to start but it was slightly lower maybe around 104 volts.

the voltage between common and start was right at 250 volts. The line voltage at my disconnect panel in the cabin is 125 volts.

Is it possible the compressor could be locked? and if it is possible is there a chance to free it up. I know the fancy tool is used to do this but what happens if you don't own one of those bad boys, 5' drop test or maybe a BF hammer?

[RV Wizard]

It looks like you might have a bad start winding in the compressor. 5000 ohms sounds too high for the work that winding should do. It could be locked rotor but most I have seen have a LRA of about 60-65 amps. The LRA should be stamped on the compressor.

[mx842]

Quote:

Originally Posted by RV Wizard It looks like you might have a bad start winding in the compressor. 5000 ohms sounds too high for the work that winding should do. It could be locked rotor but most I have seen have a LRA of about 60-65 amps. The LRA should be stamped on the compressor.

I've searched thousands of threads and nowhere does it tell you exactly what the readings should be. I'm going to check it again this evening because the compressor was hot yesterday by the time I checked it. It will probably be a little different and I'll let you know what the cold readings are.

Everything I have read says that the start to run readings will be the highest and the other two should add up to about the same as the S/R readings and that is pretty much what I have. What scale should I use on my anolog meter? I had the scale set at 1K and got a reading of 5 on the scale for the s/r reading. I'm going to bring home my digital meter this after noon and check it with that also just to compare numbers.

Also note the voltages on the the different terminals do they seem correct or not?

[Ray,IN]

Will this pdf manual help? http://dutchmen-rv.com/media/documen.../59516_603.pdf