October 4, 2026 · Mitt Patel · 6 min read
You restocked all three vans the first week of March, dropped $4,500 on capacitors, contactors, and refrigerant line sets, and now your March numbers say you barely broke even. April looks great by comparison. Neither month is telling you the truth.
Why this happens
Most small HVAC and cooling shops expense parts the moment they're bought. You get the invoice from the supply house, you code it to "parts" or "materials," and it hits your books that day. Simple enough, until you buy in bulk to fill three trucks at once.
The problem is timing. You didn't use $4,500 of parts in March. You used maybe $1,200 worth on actual jobs, and the rest is sitting in your vans waiting for April and May calls. But your books don't know that. They just see a big expense in March, and a big profit swing.
This tends to create two real problems. First, your monthly profit and loss statement becomes noise. A restock month looks bad, a coasting-off-existing-stock month looks great, and neither reflects how the business actually performed. Second, and more costly, your job costing is wrong. If you're trying to figure out whether your average install or repair is profitable, you need to know what the parts actually cost on that specific job. If all parts get dumped into one expense bucket the day you buy them, you can't tie cost to job. You're guessing at margins, which means you're guessing at pricing.
Owners who don't fix this tend to make two bad calls: they either underprice jobs because they think parts cost less than they do (since a chunk of cost already got "used up" on the books in a prior month), or they panic during restock months and cut spending or hiring when the business is actually fine.
A worked example
Say you run three service vans. Each one carries roughly $1,500 in stocked parts: contactors, capacitors, thermostats, refrigerant, fittings, and common filters. At the start of March you do a full restock, spending $4,500 across all three trucks to bring everyone back up to par.
If that $4,500 hits your books as a March expense, your March P&L takes the full hit that month, even though your technicians will spend the next six to eight weeks pulling parts from those vans as they run calls.
Now say your technicians used about $1,200 of those parts on jobs during March. Under a truck stock system, March's parts expense is $1,200, tied to the jobs where those parts were installed. The $4,500 restock becomes inventory sitting on your balance sheet, not an expense yet. As technicians use those parts on jobs through April and May, that inventory value moves into cost of goods sold, matched to the job it was used on.
The result: March shows a parts cost of $1,200, which is what actually happened. Your job margins for March reflect real material costs per job. And your balance sheet shows $3,300 (the $4,500 restock minus the $1,200 used) sitting in truck stock, which is a real asset, not a mystery hole in your cash.
How to set it up
- Pick a truck stock par level. Decide what each van should carry: a list of common parts and a target quantity for each. This becomes your restock checklist.
- Create an inventory item list in your accounting system. In QuickBooks Online, this means setting up the common parts you stock as inventory items rather than expense categories. You don't need every obscure fitting, just the parts you buy and use regularly.
- Record restock purchases as inventory, not expense. When you buy parts to fill the vans, that purchase increases your inventory asset account. It does not hit your profit and loss statement yet.
- Charge parts to jobs as technicians use them. When a tech uses a capacitor on a job, that part moves from inventory into cost of goods sold, tied to that specific job or invoice. This is the step that makes job costing real.
- Count truck stock on a set schedule. Once a month, or once a quarter if that's more realistic for your crew size, physically count what's on each van. Compare it to what your books say should be there. The difference tells you how much got used since the last count, and lets you true up the numbers.
- Adjust inventory based on the count. If the count is lower than the books expect, record that difference as a general parts expense for the period rather than trying to assign it to a specific job.
Whether this needs to run through formal purchase orders and item receipts, or a simpler monthly count-and-adjust process, depends on how many vans you run and how disciplined your team is about logging parts per job. A one-truck operation may be able to use a lighter process than a five-truck company.
What undoes it
- Not counting on a schedule. If you set this up once and never count truck stock again, the numbers drift and become fiction within a few months.
- Techs not logging parts to jobs. If a technician grabs a part and doesn't note which job it went to, you lose the ability to tie cost to job, even if the inventory accounting is otherwise correct.
- Treating small parts too precisely. Tracking every screw and wire nut as individual inventory items creates more bookkeeping work than it's worth. Track what's material to your margins, and let small hardware fall into a general supplies expense.
- Skipping the count when things get busy. The months you're too slammed to count truck stock are usually the months restocking is heaviest, which is exactly when the numbers need the correction most.
Monthly checklist
- Count parts on each van against your par level list
- Compare the count to what the books say should be on hand
- Post an adjustment for the difference, moving used parts into cost of goods sold
- Review job costing reports to confirm parts costs are landing on the right jobs
- Restock vans and record the purchase as inventory, not expense
- Spot-check that technicians are logging parts used per job
Common questions
Do I need to track every single part, down to screws and wire nuts?
No. Track the parts that actually move your margins: compressors, capacitors, contactors, thermostats, line sets, refrigerant. Small hardware can stay in a general supplies expense without hurting your numbers.
What if I run one van, not a fleet?
The same idea applies, just lighter. You still separate "parts I bought" from "parts a job actually used," even if your count is a quick walk-through of your own van once a month instead of a formal process across a crew.
Does this work differently for refrigerant?
Refrigerant is often tracked separately from other truck stock because of how it's purchased and used, and the right setup depends on your volume and how you bill customers for it. This is worth setting up specifically for your business rather than copying a generic approach.
Will this change what I report as profit for the year?
Over a full year, the difference between the two methods is the change in the value of stock on the vans from the start of the year to the end, which is usually small next to a year's parts spending. The real difference is monthly accuracy: you stop seeing false swings in restock months, and you get honest job margins throughout the year.
North Hudson Bookkeeping sets up truck stock tracking like this for HVAC and cooling businesses and keeps the counts and adjustments current every month, so your numbers reflect what actually happened on the job. The first call is free.
