Most HVAC places will give you credit for the diagnostics if you make the repair (not the service charge for the trip).

@Michael PlanteWoah that's insane, sorry to hear that.My energy company also offers a service contract in spite of the service contract they charged me a $250 diagnostics fees when ac went down but your bill just takes it to the next level

Back then it was Whole House Diagnostic Engineer.

Getting replacement boards and diagnostics can be an issue but thats the same with higher end splits as well.

Others take full responsibility for repairs, which always include a diagnostic charge from the repair company. 

@David Rosen Our limit is $500, even just a basic trip/diagnostic charge can eat up $100 of that.

Scott Gottlieb, former head of the FDA, to companies in the NYSE.US will soon have massive testing capacityConfirmed cases will grow exponentially now that testing is finally getting rolled outDon't be surprised to see 1000 confirmed cases in a dayBy the end of April to early May, it will start to plateau (depending on containment behaviors that we are currently living)Schools will be closed for this school yearThe summer heat in the northern hemisphere will help to contain the spread, although it will continue to existEvery reason to believe that the southern hemisphere will experience rapid spread as the weather cools (expect continued travel restrictions)The risk posture will improve in the Fall with the following:Point of care diagnostic (local swab testing everywhere - will allow early detection)Therapeutic antiviral drugs will be available (not a vaccine)Monthly injections of an antibody will be available (not sure what this is), particularly for medical workers and members of nursing homesThe testing capabilities that are getting put in place will provide a massive surveillance system to provide early detection until a vaccine is in placeAll of this will make the virus more manageable until we have a vaccineThe virus is very contagious (more than the flu)10x more deadly than the fluEven without death, the hospitalization rate (15%) and critical care rate (5%) are extremely high (we don't have medical capacity without containment)Mortality rate:1% overall4% ages 60-7010% ages 70-8014% ages >801 in 250 to 1 in 550 for some his age (47) - said "that's enormous"He recommended that his parents stay home for a couple of monthsHe also felt that masks should be produced and mandatedThese bullets are subject to my note taking and I am certainly not qualified in this area.

I let him know I would get someone out to look at it and confirmed with him that this was not an urgent repair as he could still use the oven.I scheduled a diagnostic for today and now the tenant wants to know if they are bringing parts, what parts he suggests they should bring, what he thinks the problem is, etc.

I guess maybe I am sometimes a little  too trusting of these "professionals" diagnostic skills.  

The issues couldn't be seen without putting gauges on the a/c etc and running diagnostics which I'm not qualified to do nor do I have the tools.