We are in contract to buy a home, and during inspection one Heating & AC company has determined that a 3 ton horizontal coil has freon leaks and needs to be replaced. The owner hired another company a week later who reports the coil is free of any leaks. The owner states all units cool the house fine, and they have never had to replace any freon.

1) What is the best way to determine if there is a freon leak?
2) What are possibilities to explain why two certified inspectors will come up with different findings about a freon leak?
3) How do we determine which report to believe? (other than getting a third opinion)

If you can establish that no refrigerant was added, the suction service superheat is between 8 and 15 degrees, and the unit is cooling the house, then you can know there probably was no leak. If you have the unit shut off after the test and wait an hour to place a refrigerant leak detector in the coil area, and there is no indication of a leak, then there might be none. In other words, science might be accepted in a fight between 'you and him.'

It would seem that a one-year written guarantee of a working unit, with an escrow deposit, could be an ordinary real estate understanding.

www.heatpro.us FREE heat/cool right-sizing

Is there really just one manufacturer of every kind of machine made, or do you really have to find out the MAKE and MODEL to get good answers?

Thank you for your quick reply. Could you tell me what a 'standard' AC unit home inspection would be to determine whether or not there is a leak? It sounds like the 'leak detector gauge' is the gold standard, but am I correct in assuming that isn't typically done in a home inspection? Is the routine test just a subjective 'guestimate' then? Do you know if requesting a 'leak detector test' would typically be an additional cost for a heating & air conditioning inspection?

If the leak is so obvious that it can't be denied:
=>The unit is running, but there is frost on the lines and there is no cooling.
=>The unit hisses refrigerant from the lines.

Then it wouldn't require leak testing.

However, I suspect the unit is running now and a leak test on a unit that can cool without a leak test is just a show. An AC repairman without a leak detector is a fake.

www.heatpro.us FREE heat/cool right-sizing

Is there really just one manufacturer of every kind of machine made, or do you really have to find out the MAKE and MODEL to get good answers?

Could you please clarify your last statement "However, I suspect the unit is running now and a leak test on a unit that can cool without a leak test is just a show"?

Do you mean that, if a unit is working and has no obvious leaks, then the 'routine' inspection would be to say that everything "looks ok" and there is 'no need to do a leak test'?

I suspect what happened in our case is that the inspector we hired, who we have an established relationship for servicing our current home, did the 'leak test' even though everything looked 'ok'. The owner's inspector is questioning 'how the other inspector found a leak because they've never replaced the freon and the unit is cooling the house.' Our guy obviously is trying to be more thorough to please us, while their guy is doing basic work to support his client. I suppose this happens in all types of business. I will find out Monday how each inspector performed their inspection, and for your info will post back here.

The unit is working, according to the owner. It cools the area of the house in question. There is no visible frost, and no hissing. They state they have never had to 'replace freon'.

Just to follow up on the above. The company that initially reported a freon leak did indeed use a leak detector. He did not quantify how bad the leak is or how soon we will need to replace the coil. (Question: Is there a way to quantify 'how bad' a leak is?)

The second inspector, hired by the current owner, only did a visual inspection and did not use a leak detector. His comments to me were, "I'm not saying there IS a leak, and I'm not saying there ISN'T a leak, but I don't suspect one so I don't see the need to use a leak detector. Besides, those things are wrong a lot."

As you've said above, science wins in this argument, and the second inspector is obviously not being thorough in order to satisfy his client. However, to satisfy my curiosity, how often are leak detectors wrong (false positives, false negatives, etc - don't want to get too far into statistics but curious!). Also, how often do companies routinely check the accuracy of their detectors?

Electronic leak detectors can get readings from other similar chorine-bearing chemicals like laundry chemicals in the same room. They are very sensitive, so can indicate freon in the oil of a very small leak that could cause loss of refrigerant over several years. Calibration of a detector is hap-hazard if at all. If the unit is and has been running with no added freon for years, then the unit is OK. Hard to prove all though.

www.heatpro.us FREE heat/cool right-sizing

Is there really just one manufacturer of every kind of machine made, or do you really have to find out the MAKE and MODEL to get good answers?

Thank you for enlightening me on this topic. You've helped save our contract from blowing up over these two conflicting reports!

All Air Conditioners leak freon. There is no seal that is absolute. I am currently designing a freon leak detector. The sensitivity is rated in 1/10th ounces per year to 1.6 ounces per year.
Simply remove the cap to the recharging valve and freon should be detectable.
Most units have up to a pound of Freon and a small leak in the order of 1 ounce per year is of little consequence to performance.
The real concern is pollution. However, the sunlight hitting the ocean produces for chlorines each year than man has produced over the entire history of Air Conditioning. So, again a small detectable leak is of little significance.