Great post wormy
will look for damaged duck work.
when I had taken the high limit out I could see alot of dust in there, also I remember the homeowner saying about water around the evap box in the summer she said however i was there for a heat no heat call.
but I will check the registers they are all low to near the floor.
I can get my flash lite and my telescope mirror and peak in at the evap, and go from there.
they had one large return with no filter and the blower is right there not more then 12 inches from the return.
after all the GOOD advice I received here from everyone,I feel very confident, I can sovle the problem tomorrow and give them there heat.
I have a bad habbit of beating myself down when i can't fix it rite away, or when its a week end and can not get parts but this Could have been solved today if I put the volt/ohm meter away and checked the duct work, registers and peaked in at the evap.
its Great to have this site to come to, loaded with great info, and good techs!
If there is no restriction in the air flow. I would make sure the unit is at BTU input. I wouldn't think anybody would change the orfice size, but someone may have changed the input or internal regulator on gas control valve may have failed.
Don't forget to put an air filter in, and remind them to change it, so you won't have to strugle like this again too soon.
sounds like the limit is working. seems you walked into something here. first if someone else was there this is on going to jump of the hi limit is not a very smart thing to do it protects the heat exchanger so that guy made a mistake right there. it wont hurt to replce it with a new one now just because you found it jump out. if there is no filter chances are the coil is real dirty on will need to be cleaned depending how long it had no filter. if the coil is ok then do a temp riase on the unit if not enought return or supply duct is to small there may not be enough iar moveing across the hx to keep it cool. what cocerns me is you said the high limit was jumped out when you got there and the unit was tripped out on the blower secondary limit in the blower compartment. for that to happen with the blower runing that hx had to be extremly hot. you may want to pull the blower and take a look at the hx if it was that hot you may be now dealing with a burn through to.
the bad part here is someone else caused the problem and now you are stuck with it. check the unit out real good and talk to the owner and explain what you found after you check everything in and on that unit.
Very good advice tinknocker.
I physically checked the registers to see if they were open and air was coming out of them with the blower on, noticed alot dog and cat hair in them, but air was blowing out of em.
then I took a real good look in opening were high limit was aboat a 1/4 inch if not more of dust and crud all weaved together in the bottom, rubbed my telescoping mirror in it don't know how any air was getting through that but registers were blowing air.
also took a good long look at blower wheel again it was good, just a little dust in blower box not much.
monday I will go back and clean evreything out.
told homeowner this is what happens when you don't use a air filter for a few years and have 2 dogs and three cats.
If there is dog and cat hair on IN the registers.
You might want to make sure dogs and cats weren't getting into the duct system hehe.
duke if there was no filter for two or three years and two gogs and three cats. i would bet dollars to donuts the coil is packed with hair and the blower wheel is too.
what i have done in this case with a hard to reach coil try to get in the coil box and spray the coil down with water real good let it soke in for a while and spray it again. once the dirt and hair are wet it will pull off like a rug in most cases all in one piece. air is deciveing dont trust the registers. hopr you did not leave the unit running with out the high limit of any type in it
again check the hx realy good never mind the one inche hole the high limit goes in pull the blower so you can realy see the hole thing and the coil to