Air Conditioning - AC Freezing, lots of little problems

My house was built in 99, last year the AC went out on it. Had someone come out and add Freon and it went to working for a few months and then started freezing up again. This time the guy came out and used the electric sniffer to look for leaks, and found a strong reading at an elbow joint. He soldered the pipe and added Freon and it last about 6 weeks. As it was winter time and I was broke I left it unserviced till this April.

The last guy was a friend of my now ex, and I was never confident he was doing his best, so got a service tech out who did another electric sniff, but couldn't find any strong readings, only a couple very small ones that when he went back was NEVER able to reproduce. He concluded that while he wasn't able to get a good leak detection that his experience tells him it is the coil. I talked to him about the UV leak test since I didn't want to pay $800+ based entirely on his gut feeling. He didn't have the dye with him, but said someone could come out and do it for no charge (since I already paid $116 for the electric test that is the least that they could do). Next thing I know the company is calling to set up appoint me not to do the test but to discuss installing a new coil! I call and get ahold of the service manager and when I mention the UV test, he says additional charge before I mention the tech said it would be free. When I ask how much he said it was $331 for a UV test, but he would knock of the $116 I already paid. Ok, $331 seems outrageous to come out dump some dye in the system and then come back in 48 hours and look at it with a light, am I missing something?

So, in the mean time I notice 2 other problems. I checked the thermostats (have zone controls) and both are wrong, the upstairs unit is little over 5 degrees off and other 3 degrees. So when it is 70 it reads 75 and 73. My ex kept trying to set it at 69 (which would be 64 because of the difference), so could the fact that it was constantly running trying to get to 64 caused it to freeze up or any other problems? Also just noticed apparently the zone control not working right, when the downstairs is supposed to be off air is still flowing through the ducts.

So, after talking to the owner of the service company, they are coming out tomorrow to do the UV test free of charge, I will have them do a better job re-applying the tape to the duct. But even if the UV test says the coil is bad and the only problem, I am not going to go with this company for repair.

I need to find out if replacing the zone controllers will correct the zones not closing properly or will I most likely have to find the dampers in the duct and look at them? Where would be a good place to shop and compatible thermostats for California Economizer zone controls?

The other suggestions I have gotten from a friend at work are to get an attic exhaust fan installed. The ducts in the attic are insulated but where the unit first goes up (big square metal box thing) to the ducts is not.

Last, and maybe most important question, the technician that was out mentioned something about last year they came out with a product to stop leaks similar to the radiator stop leak stuff for cars, but I can't find any information on that. If I indeed just have a few small leaks, is this a good option and where do I find out information about it (since I am assuming will take a certified tech) who in my area might offer this service.

Thanks,

Dave

Id replace the coil! By the time they do leak check, evac the system fix the leaks, leak check, vacuum system and recharge you could have a new coil at about the same price.

There is a product out there & my local supply houses sell a lot of it. I've never used it & don't plan on doing so. The thought of putting something in the refrigerant system to plug a leak scares me.

The other suggestions I have gotten from a friend at work are to get an attic exhaust fan installed. The ducts in the attic are insulated but where the unit first goes up (big square metal box thing) to the ducts is not.



Regarding the whole house fan (probably what is being suggested), I would like to know how well your house is insulated and if your home on hot days can remain at about mid day, at an equalized temperature between what the high temp of the day was outside, and what the low temp outside was overnight, with your windows closed (and the drapes/shades drawn). If your house at midday is anywheres within a range that nears that midway mark of those two temperatures, you have a house that is well insulated and one that does not let in a lot of heat through windows, etc.. A house like this, IMO, would not really need a whole house fan. You wouldn't want to really start sucking in the warmer outside air!

But if you have a house that reaches or exceeds the temperature of the outside temperature by midday...then your house would be a good candidate for such a fan, as this would bring in lots of outside air to cause the house to become that of the temperature of that of the outside air rather than to be warmer than what the outside air is. And to also not cause the air conditioner to run.

A good candidate house, IMO would also be one that has lots of shade on the south and west sides of the house where the air is cooler and the windows on this side of the house could then be the opened when the whole house fan is on, to draw in this outside air conditioned air. Yes, trees actually give off air conditioned air believe it or not. I have read articles on this. They actually give off btus of cool! (As contrasted by supposedly one average size house window can let in about 5000 btus of heat (a plus in the winter, but a bummer in the summer).

Regarding the uninsulated main trunk plenum: It sure woudn't hurt to have it insulated. But, just so you realize...it is more effective to have the smaller ducts that branch off it to be insulated, because there is more surface area per square inch of duct opening (compared to the big square main plenum), for which the duct could be exposed to air temps outside the duct. Illustration: Picture this if you will. Picture a 3 foot square shute. Now picture adding a bunch of 6 inch round tubes inside this shute. 36 of these will fit. If you added up all the surface areas of the 36 small round ducts you would find that their surface area would far exceed that of the 3 foot square shute that contained them all. And hence, more surface area to transfer heat. Doing the actual math, consider that 36 round tubes could fit inside the 3 foot squarte shute. The surface area of the 3 foot square shute, per every running foot, would be 12 square feet. BUT...for the 36 6 inch ducts inside the shute... since each circumference would be about 1 1/2 feet...you are looking at 54 square feet of total exposed duct area per running foot (compared to the 12 feet the square main shute has that contains them!). See what I mean? Therefore the big main plenum is actually 4 1/2 times less exposed to the outside conditions than the smaller ducts that would be branching off of it.

So, yes there will be loss through the main trunk plenum. But not near the loss incured by the smaler ducts that branch off, if those were not insulated.

I have never heard of it called a 'whole house fan', looking at something to evacuate the hot air out of the attic and thus the walls as well. I remember as a teen helping my dad wire an attic fan, specifically I remember my first lesson in making sure the electricity is off before touching wires. But yes, the house does build up heat higher than the outside temperature. The thing specifically that I noticed is underneath the bathroom sink that is connected to an exterior wall, in summer time I feel heat radiating or trapped in the cabinets when I open them.

Could someone tell me where I can find information on the additive to stop leaks?

I did get the contractor out to inject the UV dye in free of charge, was also nice enough to check out the dampers of my zone system and confirm I have bad motor, which I don't see a problem replacing myself, been thinking about adding a few more zones any way. In the planning stage of home automation and planning to have all the major rooms put on own zone.

Thanks..

Stop leak comes in many forms some effective most not. The sealer should be treated as a contaminate in the system and marked with date time and installers info. If a repair person uses his recovery unit on a system that has had sealer installed without having the proper filters, he could ruin his recovery machine. I have found sealer in automotive systems (Sells cheap at Wallly world) but have rarely found it in residential, it is known in my area as being a temporary bandaid fix that causes more problems than it cures. Others may have different opinions.

There is frequently confusion between a "whole house fan" & an attic exhaust fan. The whole house fan is a monster mounted in the attic just above the ceiling & has a set of louvers which open when the fan is turned on. The idea is to create a breeze thru the house. The attic exhaust fan just helps to prevent a build up of heat in the attic. Neither will do much, if anything, about the heat coming in thru the walls.