carrier RTU

[ccservicefitter]

Any thoughts on disabling the algorithm on a comfort link for the condensing fan motor?? Why didn't they just add a high pressure transducer to turn it on..

[y7turbo]

Why would you want to do that?

i know the condenser thermisters always fail, but thats no reason to change something from OEM.

[Dallas Duster]

Makes me wonder what your talking about , I'm thinking there is a bit more to this.

[Dchappa21]

I find most of the thermisters mounting clips break causing them to not be on the u bend... Just throw a tie wrap around them and they work fine....

I have found 2 fail open though.

[ccservicefitter]

There always is more to the story....It is controlled by an ems system and they decided to not run some of the units to save power. It is only a problem in low ambient conditions and with first stage. The failure of the thermisters has a different error code and I have replaced a few in the past too. This is a different failure. You can watch the readings and see that the thermister is fine and of course ohm them out. Mounting I agree is of course a issue and this is not a problem. The error happens only after the unit first starts then after that does not have any problems. I am just a tech not a engineer but a transducer make so much more sense...Thanks for you comments.

[Dallas Duster]

It is controlled by an ems system and they decided to not run some of the units to save power. It is only a problem in low ambient conditions and with first stage. So for the mean time I wired the first fan motor contactor to the first stage contactor. I like the idea of placing the thermister on the u bend of the coil. It will work just fine however a transducer make so much more sense...Thanks for you comments.

What's the model of roof top you working on?

[brooklyntech]

is carrier moving away from motor master fan control?

[ccservicefitter]

I don't have the model number, it was on a Target store. Carrier has that special relationship with Target. The model is particular to Target according to Carrier, I talked to a Carrier engineer and he said he would get back to me on this. Well that was like 2 months ago.

[Dallas Duster]

I don't have the model number, it was on a Target store. Carrier has that special relationship with Target. The model is particular to Target according to Carrier, I talked to a Carrier engineer and he said he would get back to me on this. Well that was like 2 months ago.

Ah now that were kinda know what we are working on ? Why is the unit not economizing? Is your enthalphy switch working correctly? The HG's are pretty good unit's I bet it doesn't even have a motormaster on it . You might want to insulate the current sensor to see if that helps.

[y7turbo]

So what is the exact problem you're having? You said something about an error code during low ambient conditions, What error code are you talking about?

[ccservicefitter]

Good point listener. High humidity in my neck of the woods for the economizer. No motormaster on this unit.
Turbo-high head pressure is the error, I don't remember the exact error #. I know the error # is different for a failed thermister.

[y7turbo]

Good point listener. High humidity in my neck of the woods for the economizer. No motormaster on this unit.
Turbo-high head pressure is the error, I don't remember the exact error #. I know the error # is different for a failed thermister.


Take the panels off where the thermisters are. I just found 5 of them broken with no error codes on the comfort link panel at 1 retail store. They would still read temperature, and would bring on the fans but late. I think they were sensing the heat generated by the coil but they were not directly sensing the coil temperature.

Now every unit I work on with those condenser thermisters, I take the panels off to check the sensor. You would be surprised on how many I find with broken clips and are just hanging next to the coil.

Anyway, I dont know if that helps, but its something to look into.

good luck.

[ccservicefitter]

Turbo- I will look into it thanks for your help

[just_opinion]

Hey Turbo,

While you are at it, go out and fix it for him/her too. He/She is too busy reengineering the control that has been working for more than one location or weather and many years.

That's is why you guy may see me got all upset about some questions around here. And they are from tech who got paid to perform the task and to investigate for problems.

I wish ther is a "automobile talk" website and see question like "I got a blue car and it makes funny noise. Can you guy help? By the way I am a car mechanic who get paid"

Sorry. Got to get it off my chest.

[ccservicefitter]

Hey Turbo,

While you are at it, go out and fix it for him/her too. He/She is too busy reengineering the control that has been working for more than one location or weather and many years.

That's is why you guy may see me got all upset about some questions around here. And they are from tech who got paid to perform the task and to investigate for problems.

I wish ther is a "automobile talk" website and see question like "I got a blue car and it makes funny noise. Can you guy help? By the way I am a car mechanic who get paid"

Sorry. Got to get it off my chest.
I ask manufacturers and service techs questions all the time. I believe that makes me a better tech. I was using this web site as a resource and I should rethink that. I asked the Carrier Factory Service Engineer about this problem and he did not have a solution for me and then I made the mistake of researching the problem further. I'm I on the right track here?

[Dallas Duster]

I ask manufacturers and service techs questions all the time. I believe that makes me a better tech. I was using this web site as a resource and I should rethink that. I asked the Carrier Factory Service Engineer about this problem and he did not have a solution for me and then I made the mistake of researching the problem further. I'm I on the right track here?

It's a 2 way street sometimes . We assumed that you had checked the unit out thoroughly before asking for help. How silly is it going to be if the clamp on sensors are just broken like Chappa said . It can be just that simple . No reason for everyone to get upset over it. You can't fix anything properly if the unit is not 100% operational as far as the sensors not being broken. Let us know what you find.

[Dallas Duster]

It's a 2 way street sometimes . We assumed that you had checked the unit out thoroughly before asking for help. How silly is it going to be if the clamp on sensors are just broken like Chappa said . It can be just that simple . No reason for everyone to get upset over it. You can't fix anything properly if the unit is not 100% operational as far as the sensors not being broken. Let us know what you find.

I just wanted to follow up on this thread for the guys working on Carrier 48/50 HG , PG and PM units. The condenser coil sensor style has changed to a more reliable clamp .

[y7turbo]

I just wanted to follow up on this thread for the guys working on Carrier 48/50 HG , PG and PM units. The condenser coil sensor style has changed to a more reliable clamp .

I just installed a few last week. Its just a thermister probe that comes with a seperate steel clip to clip the probe to the U bend. Looks like its going to last longer than the older style..

[ccservicefitter]

Goodlistener I appreciate your follow up on this post. I did end up replacing the sensor and clip, it did appear to be a lot better of a design. I still say why not use a transducer instead of thermisters.

[Dallas Duster]

Goodlistener I appreciate your follow up on this post. I did end up replacing the sensor and clip, it did appear to be a lot better of a design. I still say why not use a transducer instead of thermisters.

Yeah the new one still looked kinda cheesy to me. When another tech showed me what the sensor looked like I thought he was givin the wrong sensor . So I called up the engineer to confirm the new one. But I do also agree about the transducer but I'm certain it won't be long until there will be one.