Buying a Hvac: Due Diligence Checklist & Red Flags (2026)

Red flag: Less than 20% of total revenue comes from recurring agreements—means cash flow is unpredictable and dependent on one-off repair calls.

Ask: What dollar amount and percentage of total revenue comes from annual maintenance contracts, and what is the average contract renewal rate?

Red flag: Over 30% of receivables are past 60 days, or one commercial property management group accounts for more than 40% of revenue.

Ask: Can I see the AR aging report and a list of the top 10 customers by revenue with their payment history?

Red flag: No balance-sheet reserve for warranty work, yet warranty claims average 3% of revenue, indicating future profit erosion.

Ask: How do you track and fund warranty callbacks, and what has the actual warranty expense been as a percent of revenue for the last three years?

Red flag: Seller's add-backs include personal vehicle leases, family cell-phone plans, or inflated officer salaries not related to a replacement operator—inflating SDE by 30%+.

Ask: Please itemize every add-back on the P&L with actual receipts, and explain which expenses will disappear the day I take over.

Red flag: Inventory listed at original cost but contains R-22 condensers and other phased-out refrigerant equipment that can't legally be installed.

Ask: What is the current market value of the parts inventory, and what portion is obsolete or tied to equipment using phased-out refrigerants?

Red flag: Only the owner holds the required HVAC contractor license, and no other employee has a journeyman or master license—leaving the business unable to pull permits post-sale.

Ask: List every field employee with their license type, number, expiration date, and whether they have EPA Section 608 certification.

Red flag: Average van age exceeds 8 years with 200K+ miles and no replacement schedule; three of six vans have check-engine lights on during inspection.

Ask: Provide maintenance logs, current mileage, and replacement history for each service vehicle, and explain any major repairs pending.

Red flag: Calls are still routed through the owner's personal cell phone with no after-hours answering service, and 20% of service calls are missed.

Ask: Walk me through how a typical service call is received, dispatched, and closed—what software do you use and what are your average response times?

Red flag: Recovery machines, vacuum pumps, and manifold gauges are over 10 years old and not compatible with newer A2L refrigerant requirements—immediate $15K+ replacement needed.

Ask: Can I see an inventory of major diagnostic and refrigerant-handling tools with purchase dates and calibration records?

Red flag: No written agreements with key supply houses and the primary subcontractor for ductwork is the seller's brother-in-law with no formal pricing agreement.

Ask: Who are your top three parts suppliers and subcontractors, what are the payment and pricing terms, and are there any exclusivity or family relationships?

Red flag: Market has more than 10 listed HVAC contractors per 10,000 households and the business has no differentiated offering—average ticket is trending down 5% per year.

Ask: How many direct competitors serve your primary zip codes, and what has happened to your average service ticket and total completed jobs over the last three years?

Red flag: Over 60% of revenue comes from new residential construction installs—exposing the business to a housing downturn and builder pricing pressure.

Ask: Break down revenue by new construction install, retrofit/replace, and service/repair for the last three fiscal years.

Red flag: 90% of revenue occurs in June–September with negative cash flow in Q1 and Q4, requiring a line of credit just to cover payroll in winter.

Ask: Provide monthly P&Ls for the last 24 months so I can see exactly how revenue and net income fluctuate by month.

Red flag: Google rating below 3.8 stars with multiple unresolved complaints about no-shows, and 80% of leads come from a single home warranty company that dictates pricing.

Ask: What percentage of new leads come from Google/online, referrals, and third-party platforms like home warranty companies, and can I see your online review history?

Red flag: State license is in the seller's personal name and cannot be reassigned; the business would need a new license and a qualifying agent, which could take 4–6 months and freeze operations.

Ask: Is the HVAC contractor license held by the business entity or an individual, and what is the exact process and timeline for me to become the qualifier?

Red flag: No refrigerant usage logs, and a tip from a tech suggests the business has been venting refrigerant—exposing the buyer to fines up to $44,539 per day.

Ask: Provide the last three years of refrigerant purchase and recovery records, and confirm no EPA violations or pending enforcement actions.

Red flag: Lease has a blanket non-assignment clause and landlord refuses to negotiate; the shop is month-to-month and located in an area the landlord plans to redevelop.

Ask: Can I see the current lease with all amendments, obtain written landlord consent for assignment, and get a renewal option for at least five years post-closing?

Red flag: No signed non-competes with key techs, and the lead installer has a spouse who runs a competing HVAC business—ready to siphon off accounts.

Ask: Do all technicians and office staff have enforceable non-compete and non-solicitation agreements, and will you provide a non-compete for yourself for five years and within a 50-mile radius?

Red flag: Multiple pull-permit records show final inspections never completed, leaving liability for code violations on the buyer.

Ask: Pull a permit history report for all jobs from the local building department—are there any open permits or unresolved code enforcement issues?

Red flag: Two of the three senior techs have already given informal notice they'll leave upon sale, and they're the only ones with the relationships with the top five commercial accounts.

Ask: Which employees are absolutely critical to retain, what are their current compensation and tenure, and what retention bonuses or incentives do you recommend I offer?

Red flag: No plan to introduce the buyer to the top 50 recurring customers—seller suggests a generic email blast after closing, risking immediate defection.

Ask: Will you personally introduce me to the top 20 commercial accounts and key property managers at least 30 days before closing, and what will the written customer transition letter say?

Red flag: Business phone number is on the seller's personal family plan and cannot be separated; the Google Business Profile is tied to a personal Gmail account.

Ask: Verify the business owns its phone number separately and show me the admin access for the website domain, Google Business Profile, and any directory listings—what is the transfer process?

Red flag: Seller offers only a 'two-week phone consult' but is moving out of state and will be 3 time zones away, leaving no hands-on transition for the commercial estimating software.

Ask: What specific on-site and remote training will you provide for the first 60 days, and will you be available to join me on the first round of commercial bid walks?