I’ve been seeing a lot of HEIL furnaces and AC units lately (new ones). Does anyone have info on their Model and Serial number codes? That’s a brand that my notes don’t cover. I don’t recall seeing any older ones, so I’m thinking that they might be a new brand name (but that’s just a guess, based on my perception.)
HEIL - See International Comfort Products, LLC
The model number and serial number are printed on the unit’s rating plate normally located on the outside jacket of the unit. Model numbers appear in the following typical format: PGC036K060A; serial numbers appear in the following typical format: L004112345. To determine the date of manufacture of an Heil unit, use the first four numbers of the serial number. The first two numbers represent the year, and the third and fourth numbers represent the week of manufacture. In the sample number provided the unit was manufactured the 41st week of 2000.
HEIL Recall - Originally issued 19 Oct 2005
Awesome! Thank you very much Larry!
I’m glad I could help…
I just ran across this one today and that system doesn’t make much sense to me.
MFr No. 94356
Serial No. H 55120465
Model No. CU229AQD1C
Thanks!
Something is strange with yours… Notice the serial number isn’t stamped like the other numbers but is a sticker covering the area up. Wonder whats up with that?
I did notice that,too. That’s why the pic was included. The furnace was an oil burner with a DOM of 2000. The A/C was quite a bit older. The house was buit CIRCA 1976. That doesn’t even help. That’s the reason for my post. 
I would probably make a comment on the lines of: Was unable to determine the date of manufacture of the AC compressor. Estimate age to be between 20 and 25 years old. The unit was operating property at the time of the inspection, however he normal life expectancy of an AC compressor is less than 15 years. Recommend budgeting for a replacement in the near future.
I just pulled that out of the air, so you would want to make appropriate corrections and edits to your situation.
Heil - (1980 - 1989)
Serial Number Format H61139301
Using the first and second digits of the serial number H61139301 you will find the yar of manufacture. The first digit (Always the letter “H” for the 1980’s.) is the decade of manufacture and the second digit is the individual year within that decade. The sample number provided is from an actual unit that was manufactured in 1986.
In your serial number Serial No. H 55120465 the unit was manufactured in 1985.
Hummm,
Prestons list that model number as being from 1975 only.
How you been John, long time no see 
Regards
Gerry
Prestons puts the model number as manufactured between 1973 and 1978
Efficiency ratings varied throughout those years as well.
With an altered serial number tag the possibility of something significant having been replaced in 1985 could be considered that changed the efficiency and which required a new or updated serial number but allowed the model # to remain the same.
Without repair receipts or some sort of service record history it becomes difficult to determine.
Regardless, 25-30 years estimated age would seem appropriate for this circumstance.
Thanks!