I don't know of a service problem with the A/C evaporator, so I personally wouldn't bother with the A/C side. I just retired after years in the HD end of the part business, Clutches, Brakes, Air Compressors, Industrial Friction and of all the vendors I dealt with on the HD side I can't name one who's doing cooling system parts in the US, and I assume that like most of the parts on our trucks they are out sourced to foreign countries.
It used to be you could go to the major chains of part stores and you had your choice of American made and foreign made Clutches, Brakes, Radiators, etc... . today I know the people I dealt with no longer carry American made. The cost of economics here in the US make it almost impossible for a manufacturer to compete with wages. . Had I offered a US made product it would have 4-5 times the price.
I used to purchase OE Clutches from vendors who paid their employee's less per month than I paid in medical benefits for them let alone the Social Security taxes and wages.
When you factor in the manufacturing costs of the raw materials, and than the actual manufacturing costs its almost impossible...
A good example is a center plate for a Class 8 truck... US manufactured cost at $48. 75 fob Chicago, from our off shore vendor $17. 50 fob our door. And in this case, the off shore manufacturer held better tolerances in manufacturing than the US counter part. The same company in another plant makes in tank fuel pumps and gauges... something like 3 million units a year... 90% of that business was OEM... .
It will be interesting to follow this thread, some of the vendors, BCA, Federal Mogul, Arvin Meritor, that I'm personally aware of sell parts made in their off shore plants, but are traditional US companies.
If a new heater core is, lets say $65. 00 would you be willing to pay $240. 00 for the same product made in the US... .