Professional Member*
yes im replacing a condenser on a old trailer,the old condenser had a transformer in it so did the furnace....so i added a transformer to the new condenser...now i can only get the ahu to run but not the condenser....what do i need to wire this
Former Site Administrator- Now Retired
Mr. Fredbear
Although you may not want to hear this right now, this is not a site that is allowed to tell a homeowner how to do it yourself. I am very sorry.
Second. I can tell you are serious about getting help, can you give us details about what you are working on, model number and maybe we can direct you to the right direction.
Professional Member*
im not a home owner,just trying to help a technician on the job......the old condenser had 5 wires,with transformer,and alos a transformer on the inside....cant he just do away with the one outside and put one inside,im not very familiar with 20 year old trailer units....most of what i do is commercial and residential installation...also remeber this guy called me so im not looking at it...to me it sounds like he needs a common wire...like i said i would have to be there to see...i just thought i might get a simple solution from someone that has ran across this
Former Site Administrator- Now Retired
can you get from him the model and manufacturer of the condenser and ah?
Professional Member*
Just trying to help a tech. an a/c tech? boy he's in trouble the blind leading the blind.Originally posted by fredbear
im not a home owner,just trying to help a technician on the job..
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Professional Member*
thx for your help...but he got it.had to run a extra common outside,to the common in the furnace...im familiar with transformers on the condensers feeding the air handlet ....just installed 6 7 and a half ton tranes,which was a breeze but trailers stump me...thx for your time
Former Site Administrator- Now Retired
YUP... I can't see it either.. now wifey is calling me to go to the store...
ta ta...Poof
Professional Member*
it must be easy...because the blind just fixed itOriginally posted by mrbillpro
Just trying to help a tech. an a/c tech? boy he's in trouble the blind leading the blind.Originally posted by fredbear
im not a home owner,just trying to help a technician on the job..
God Speed, Jim. We'll miss you - 2-26-23
You originally said YOU were installing the new condenser.Originally posted by fredbear
im not a home owner,just trying to help a technician on the job......the old condenser had 5 wires,with transformer,and alos a transformer on the inside....cant he just do away with the one outside and put one inside,im not very familiar with 20 year old trailer units....most of what i do is commercial and residential installation...also remeber this guy called me so im not looking at it...to me it sounds like he needs a common wire...like i said i would have to be there to see...i just thought i might get a simple solution from someone that has ran across this
Why would the new unit need a common, if the old one didn't.
Professional Member*
the old condenser had five wires,the new one 2,i told him to try and run a third wire as common to the condenser,and tie it to common on the treminal board,and it worked,so the system works off 2 transformers..all i can say is that the condenser and the ahu were not getting a common wire somewhere....i hate trailer units anyway,plus im talking to guy on the phone that i can barely hear...i know on the tranes i just put in they had 4 wires...2 commons,yellow ire,and a hot wire
Professional Member
This makes no sense. Usually only one unit needs a transformer because the transformers job is to lower the main voltage down to 24 volts to be used as control voltage. It doesnt matter which unit it is in as long as it is wired right.I have no idea why on earth you would add a second transformer. No offense but I bet this will be in the hall of shame if Payson sees it.
Professional Member
Ive seen quite a few units over the years with two transformers.....all in mobile homes.... I put a few in quite a few years ago when I was doing some installs on the side for a mobile home place, thnk they were miller brand ....never understood the reasoning behind it... you see a lot of stats with seperate rh and rc terminals though, thats the kind of system the seperate rc and rh are for.
Professional Member*
im glad someone else has seen this,but what is the purpose of 2 transformers?
Regular Guest
The reason is that the transformer in the furnace is a low va rated one. It does not have enough capacity to power the a/c controls, only the furnace. The second transformer in the a/c unit only powers the cooling side (compressor contactor and indoor blower relay)unless someone rewires the system to use only one transformer.
Professional Member*
I've seen several in old add on AC. Remember when every house wasn't built with an AC.Originally posted by countryboyinar
The reason is that the transformer in the furnace is a low va rated one. It does not have enough capacity to power the a/c controls, only the furnace. The second transformer in the a/c unit only powers the cooling side (compressor contactor and indoor blower relay)unless someone rewires the system to use only one transformer.
Trailers can be a real bitch. especially the ones with AC and a two wire thermostat.
Regular Guest
This is the correct answer, Learned the hard way once, I have rewired the indoor unit with a bigger transformer many times, I think it is cheaper then buying the kit. Not sure but I think that is the reason I have done it. If I remember right I first figured this out because I did not read the instructions and only pulled a 2 wire to the condensor,and did not want to pull a new wire. Prior proper planning prevents piss poor proformance. If they rewired the condensor the same way they took it out there should not have been any problem. Wire should have been adaquit and nothing should have had to be changed inside the furnace. Probably have it wired now so its only using the indoor transformer.If this is the case you will find out sooner or latter when the indoor transfomer fails and he can sort out this mess.Originally posted by countryboyinar
The reason is that the transformer in the furnace is a low va rated one. It does not have enough capacity to power the a/c controls, only the furnace. The second transformer in the a/c unit only powers the cooling side (compressor contactor and indoor blower relay)unless someone rewires the system to use only one transformer.
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