Not knowing the location of the OP..... I've had excellent service and fair pricing from https://texasdiscountair.com/
DFW area company...
When my HVAC system was on life support they helped with small services (diagnostics and top-up, load checking) for a minor service fee or even free. I recommended them to a few friends who had similar great experiences...
When my 5-ton unit finally died (the fan motor smoked and filled my downstairs with enough smoke that we called the FD) on a hot summer Sunday last year, I called them and they answered the phone at 5PM (Sunday) and were out on Monday morning to install the replacement for what I thought was a very fair price and later found out was a good amount under the price paid to other companies by several neighbors (via Nextdoor).