Evaporator Coil Question

Would you recommend an evaluation by an HVAC technician for this system’s evaporator coil. It was an InterTherm, age = 8 years old. Some corrosion was on the base of the coil unit. How much corrosion is acceptable?

I rarely view the evaporator coil as part of my inspections…is this something that should be looked at routinely???

Also, the only filter was a fiberous mat sitting directly on the coil…there was no filter in the return otherwise. Is this OK???

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The installation appears to be improper, the coil is in very poor shape for 8 years, sitting angled possibility allowing air to flow around it, and it is plugged with dirt because of the filter situation. Protect your self by listing this in your report and that it needs further evaluation by a qualified HVAC professional

Standard report paragraph:

I agree with Russel Rays statement, I however I personally leave out any type of statement like if seller cannot prove that heating and cooling system has been inspected/serviced within the past 12 months Only because it’s my personal opinion that too many service technicians do not know code, and don’t care, they often over look major issues or create them while on the job. They may be good in restoring operation but often lack the skills to properly evaluate an HVAC system from the standpoint of a house sale/inspection, that’s why we see so many violations in the HVAC area.

I just recommend that the HVAC system needs further evaluation by a qualified licensed professional and I put why I think so, It’s now off my back completely, that way I avoid the statement from the seller, “well is was serviced yesterday and he did not find anything wrong” because it might have been serviced, but the tech just did not care enough or know enough to report on this type of condition

(Normally every company will have at least one knowledgeable person be it the owner, an engineer or hopefully a fully trained sales person and yes some times the lead service tech or manager. But not every one will be qualified for this type of evaluation)

My 2 cents

Good pics.

I think we actually are doing the same thing, i.e., putting the liability on someone else. I just go a little further than you do. In my case, if I don’t find any problems, my recommendation is still there, i.e., “if the seller cannot prove that it has been inspected/serviced within the last 12 months,” then have it serviced/inspected before close of escrow. I do that because I don’t take furnaces/cooling condensers apart. Especially with some of these new, high-efficiency, closed systems, there could be a cracked heat exchanger. The coolant level could be low because of an interior leak that I can’t detect.
So while everything might work at the time of the inspection using normal controls like a normal homeowner would use on a normal day, my recommendation requires a little more.

And with our climate here, too many of us don’t use our heating and cooling systems. But on that one day nine months after escrow closed when the 100-degree Santa Ana winds arrive, and the cooling system doesn’t work, and they come to me, well guess what? Did the seller prove that it had been serviced/inspected in the previous 12 months? No? Did you have in serviced/inspected before close of escrow? No? Tough luck. Don’t come to me.

We will have to disagree on what HVAC techs know and don’t know, probably for our specific areas only, though. Here in California they are licensed and regulated. So they are considered much more expert than I am as an unlicensed home inspector.

Someone’s words are not proof (“well it was serviced yesterday and he did not find anything wrong”). A written receipt from the HVAC company, dated, signed, showing charges, etc., is proof.

I agree.
Here in Ohio the owner holds the license but the individual techs do not, they only have to have a EPA cert for refrigerant handling, no skills testing or journeymen’s type of license is required on the technician level

Same way here. We have guys working for HVAC contractors during the day and going to school at night trying to learn what they need to know during the day. If each truck did not have a trained tech on board a lot of those fellas would not know what to do or what they are looking at. Several owners I know personally put the new guys on the duct crew for a season to let them learn the ropes and go to school to earn while they learn. I use the occasion to educate the new owners of the home on what they should be doing to maintain their equipment and what questions to ask the tech if and when they call them out for repairs. I hear all the time people about how they just had the system checked and it “only” needed a “pound” of Freon. I then ask them did they show you where it was leaking. The normal response is a blank stare and a “Should they have?”

Thanks guys for your advice on reporting. But I’m still interested to know if you routinely look at evaporator coils.


I do if its possible. I report as to the condition and if it appears to be in need of maintenance. A clogged coil will dramatically impact the way it performs.

Never…usually very limited access.

Joe, Is this unit located in a manufactured home?

I’ve rarely seen one. They are almost always closed up with no access panels.

On a lot of units you can see the bottom of the evap coil by looking up through the bottom once you remove the filter at the grill. I carry one of those large cheap mirrors you find in the automotive store or section of Wally World. I can usually see enough of the coil to know whether or not it is badly clogged up with petrimous matter, reducing the air flow. On gas furnaces this is not possible as the evap coil and housing is located on top of the furnace and not visible. I do check whenever possible. One thing you can usually see is the circulating fan and its housing. If it is clogged up with dust caked on the cup of the blades and motor housing it is a pretty good chance the evap coil is dirty as well. This come from one thing…Cheap (or no ) filters.


This was definitely a poor quality installation. Most of the newer evap coils are plastic. That one is pretty rusty. Any leakage from the coil will go into the electric elements and controls. From there it will go into the ductwork below. The filter lying on the coils is not the best place for the filter to be. Best if it was in a filter grill or in the cover. Most MH units have made provision for a filter in the door/cover panel. Since this unit is downflow the top of the coil will be dirtiest.

My last post says I’m not a member I beg to differ. NACHI ID: NACHI06011670

Ah it’s fixed now.