Our program includes both a 9-month residential/light commercial certificate as well as a 2-yr AAS addressing commercial HVAC service, maintenance, and operation. We teach both new students just entering the field as service technicians and/or installers as well as providing upgrade training for long-time technicians. I primarily use manuals and data from the websites of the manufacturer and/or manufacturer reps to address service, maintenance, and operations. It is far superior to any textbook since it is material addressed by the industry, not an academician, thus the student is more accepting of what is being taught. Not all of what I list below is 100% useful, but I use elements of virtually everything on this list and more.
All About Circuits
https://www.allaboutcircuits.com/textbook/
Copper, Soldering, Brazing
https://www.copper.org/publications/pub_list/soldering.html
http://www.wes.ir/files/3686573BrazingHandbook.pdf
https://archive.org/details/Soldering_Brazing_Welding-A_Manual_of_Techniques_D._Pritchard
https://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf
ECM Motors
https://www.genteqmotors.com/assets/0/96/101/111/112/222548e1-3a94-4465-ae93-3ac96782fea5.pdf
https://www.genteqmotors.com/assets/0/96/101/111/112/4c713fab-2d3f-465e-bfb1-94fa5e0d052a.pdf
https://www.priceindustries.com/content/uploads/assets/literature/manuals/section%20g/ecm-motor-troubleshooting-manual.pdf
Induction Motors
http://www.fasco.com/distribution/fasco-motor-facts/fasco-facs-english/
http://css.wsu.edu/wp-content/uploads/2012/09/Motors1.pdf
https://new.abb.com/docs/librariesprovider53/about-downloads/low-voltage-motor-guide.pdf
VFDs
https://customer.honeywell.com/resources/techlit/TechLitDocuments/63-0000s/63-7062.pdf
I've not found a good generic resource on drives including the one listed above. I prefer to use the drive manuals that come with the VFDs with which I teach. We have Automation Direct GS1 and GS2 drives as well as ABB HVAC drives used to operate our pumps and our Air Handling Unit.
https://cdn.automationdirect.com/static/manuals/gs1m/gs1m.html
https://cdn.automationdirect.com/static/manuals/gs2m/gs2m.html
https://library.e.abb.com/public/debb3e43999f4e55c1257d0b00267491/EN_ACH550_01_UM_G_A4.pdf
Control (I teach control using the Tridium JACE 6 and JACE 8000)
- I have written my own fundamentals of control for the so-called control theory
- I use the manuals that come with the Tridium Workstation AX software. This won't help if you do not use Tridium Niagara or a rebranded version of the JACE
- When I teach BACnet and Modbus, I use the manuals for the equipment that use those communication protocols. For example, the Automation Direct Drive manuals above provide adequate discussion of Modbus. The ABB Drives have a separate manual that addresses setting up BACnet communications for their drive.
https://library.e.abb.com/public/3a7f1befeb5556dbc12572dc002365b3/3AUA0000004591_REVD.pdf
Bell & Gossett
http://bellgossett.com/training-education/training-manuals/
Marley Cooling Towers
https://spxcooling.com/pdf/Cooling-Tower-Fundamentals.pdf
Cleaver Brooks Boilers
http://cleaverbrooks.com/reference-center/resource-library/boiler-book/index.html
Trane
The Trane materials are not free; in fact, I consider them expensive. But it is possible to ask Trane for permissions to use pdf versions and place them on your course management system. Go through your local Trane Distributor.
Baltimore Cooling Tower
http://www.baltimoreaircoil.com/english/knowledge-center/resource-library
Belimo Actuators
Catalog for damper actuators and valves
http://www.baltimoreaircoil.com/english/knowledge-center/resource-library
Knowledge Center
https://www.belimo.us/en_US/solutions/links/documents.html
Much material here, but the damper applications guide is great.
VAV Systems
https://www.titus-hvac.com/file/7564/terminal%20units%20eng_guidelines2013.pdf
https://www.kele.com/kele-solutions-articles.aspx
TSI / Alnor (for airside T.A.B. work)
Functional Testing Guides
Do not be confused by the word 'design'. This is part of the commissioning process which necessarily employs many technicians
Titus
https://www.titus-hvac.com/file/11072/AirBalancing_AG_2016.pdf
Air Balancing Guide that also addresses fans and fan curves
Any Number of YouTube Videos
I also use the owner and installation manuals for my lab equipment i.e.: AHU, Chiller, Boiler, geothermal, Pumps, Fans, VFDs, valves, dampers, control, etc. The students appreciate the
ability to learn from those documents.
If you are an ASHRAE, AHRI, ACCA, RSES, etc. member, don't forget to use magazine/journal articles. I use many ASHRAE articles to address what the designer was suppose to do so that my students can understand how they operate so they can be properly serviced.
This is actually a short list. There is nearly anything you want available for free and for legal use and distribution from manufacturer's websites. Most manufacturers want these distributed and used by students and technicians...it's free advertising. However, it does take effort to use them in the classroom since they will not necessarily fit an individual's teaching style or the progression of your specific program. I've made it work and the students appreciate the literature to which they've been exposed and are able to use it in the field.
Hope these materials help.
RKM