A useful parking AC request for quotation describes the working problem before asking for a price. Suppliers need the vehicle, operating conditions and required cooling period to propose a meaningful configuration. A request for “24V AC, best price” leaves too much open to interpretation.
Describe the vehicle and application
Provide the vehicle make, model, model year and relevant cab configuration when known. Include dimensioned installation information and photographs. State whether the project concerns a sleeper cab, day cab, RV or equipment cabin, and identify any restrictions on roof or body modifications.
Explain the daily work pattern: long overnight rests, short delivery stops, loading queues or occasional leisure use. Note occupancy, door openings and the climate in which the equipment will operate. Distinguish required conditions from preferences.
Define the energy and installation boundary
Identify the available electrical system and any existing auxiliary battery or charging equipment. Ask the supplier to state what additional components are required, subject to qualified installer and vehicle approval. Include the intended period of engine-off operation and other loads sharing the supply.
Give the available mounting envelope, indoor clearance and service-access constraints. Require a proposed installation drawing for the exact configuration. Avoid accepting a general family photograph as a fitment confirmation.
Request comparable evidence
- Current model-specific datasheet and installation manual.
- Cooling and electrical-input information with test conditions.
- Noise information with the measurement basis stated.
- Proposed sample test and agreed acceptance criteria.
- Applicable documents for the destination market and exact supplied model.
- Warranty, spare-parts identification and support arrangements.
Ask the supplier to mark unknown or unvalidated items explicitly. A clear limitation is more useful than a broad claim that the product fits every truck or every climate.
Specify the commercial deliverable
State the sample and expected order quantities, delivery destination, preferred timing and branding or packaging needs. Ask for an itemized quotation showing included accessories, exclusions and the scope of commissioning support. Confirm the configuration and revision covered by the price.
The final RFQ should let several suppliers quote the same outcome. Use the responses to narrow the shortlist, then validate the selected system on a representative vehicle before wider rollout. This gives both buyer and supplier a practical foundation for pricing, acceptance and ongoing support.
Which documents should be attached to a parking AC RFQ?
Attach the evidence a supplier needs to design for your vehicle rather than describe the vehicle in prose alone. A short package is enough: photographs of the cab exterior and interior, a dimensioned sketch of the intended mounting area, a diagram of the existing electrical supply, the vehicle identification details and a note on any body or roof restrictions. Suppliers who receive this package quote a configuration instead of a family of products. Where the fleet contains several cab variants, say how many of each and identify which variant is the majority, because that proportion should drive the proposal rather than the most unusual vehicle in the yard.
- Vehicle make, model, model year and cab type.
- Roof or body photographs, including any existing equipment already fitted.
- Dimensioned sketch of the mounting area with available height.
- Electrical diagram showing battery capacity, charging source and existing loads.
- Interior photographs of the sleeper or cabin area to be cooled.
- Any workshop or regulatory restriction that limits modification.
Label the photographs with the date and the vehicle identifier so that the supplier can refer to a specific image in the technical response. Unlabeled photographs produce questions that cost a week each, and the answers arrive after the quotation deadline rather than before it. Keep the photo pack small enough to send by email in one message, because a link that expires or a folder that requires an account is a reliable way to lose a week. Compress the images to a readable size and keep the originals available on request, since a supplier may need the full resolution to measure a roof curve.
State which documents the supplier must return. A quotation without a dimensioned installation drawing, a model-specific datasheet and a statement of included accessories cannot be compared with another quotation, and asking for these at the bid stage is far cheaper than obtaining them after selection. Where a supplier cannot produce a drawing, treat that as information about its engineering support rather than as an administrative delay. Where drawings arrive late but complete, note the delay in the evaluation record instead of penalizing the technical content, so the score reflects the proposal rather than the calendar.
How do you describe the electrical supply without guessing?
Describe the electrical system as it is, not as it should be. Record the nominal voltage, the battery capacity and chemistry, the alternator or charging arrangement, the condition and age of the batteries, and the other loads that share the supply during an engine-off period. A supplier designing against an assumed 24V system with healthy batteries will propose something different from one designing for a mixed fleet with aged batteries and a second refrigeration load. Both proposals can look reasonable on paper, which is exactly why the brief must remove the assumption rather than leave it to chance.
Separate the measured information from the estimated information and mark each clearly. If the battery capacity is unknown, say so and state what the fleet currently achieves in practice: how many hours of engine-off cooling drivers actually get before a starting problem appears. Practical experience is useful evidence, provided it is presented as experience rather than as a specification. Ask the supplier to repeat the assumptions back in its response, so a misunderstanding becomes visible in the quotation instead of in the first hot night of the season.
Ask the supplier to state what additional components the proposed configuration requires and who is expected to supply them. The answer often reveals whether the quoted unit is genuinely a complete solution for your duty or the visible part of a longer list that your workshop will have to complete at its own cost. Ask for the additional components as itemized lines with prices, so the gap between bids reflects equipment differences rather than differences in what each bidder forgot to mention.
Include the intended charging pattern as well. A vehicle that runs long daily routes and parks overnight has a different energy balance from a vehicle that spends most of its week stationary at a depot, and the RFQ should make that pattern explicit so the supplier can size the proposal against it rather than against a generic assumption. If the charging pattern is irregular, say that too, and ask the supplier to state the risk it creates for battery health over a season of use.
How should the RFQ be structured so answers arrive in comparable order?
Number the requirements and ask suppliers to answer in the same numbering. A structured RFQ turns several long narratives into one table you can read across, and it makes omissions visible immediately. Keep the numbering stable between versions as well, because renumbering a revised brief quietly invalidates the answers bidders already prepared. Circulate the numbered list internally first, so that operations, maintenance and finance each add their own requirements before the brief leaves the building.
Group the requirements into blocks that follow the decision: vehicle and application, technical configuration, installation and commissioning, documentation and compliance, commercial terms, and service support. Within each block, ask one question per line and state the expected form of the answer, whether a value, a document reference, a yes or no with explanation, or a proposal. Blocks that follow the decision order also make the internal review easier, because each reviewer can read the section they own instead of the entire submission.
Mark each requirement as mandatory, desirable or informational. Suppliers need to know which items can be discussed and which will disqualify a bid, and the distinction protects you from a late argument about whether a missing document was ever required. Mandatory items should be few, specific and genuinely necessary. Everything else belongs in the desirable list, where a supplier can explain a departure without feeling that the bid is lost before the technical discussion begins.
Reserve a section for the supplier's own questions and for any deviation they propose. A supplier who proposes an alternative configuration is often responding to something in your brief that deserves a second look, and an RFQ with no room for that conversation tends to receive compliant but unimaginative answers. Note which alternative proposals you seriously considered and why you set them aside, because that record answers the same question when a supplier raises it after the award.
What response format should the RFQ require?
Require the response in a defined structure: a completed requirement table, a technical proposal with drawings, an itemized price schedule, a delivery and support statement, and a list of deviations. Without a fixed format, the comparison becomes an exercise in reading style rather than in evaluating substance, and the best-written bid wins regardless of merit. Give the evaluation group the format before the bids arrive, so nobody spends the first meeting redesigning the page they are reading.
| Section | What the supplier returns | What it lets you compare |
|---|---|---|
| Requirement table | Answer per numbered line, with document references | Completeness and clarity of the offer |
| Technical proposal | Configuration, drawing, duty assumptions | Fitment and expected performance |
| Price schedule | Unit, accessories, packing, delivery basis | Cost structure across bidders |
| Delivery and support | Lead time, sample plan, spares and training | Practical readiness after award |
| Deviations | Named departures from the brief with reasons | Risk and negotiation agenda |
Set the page limit and the file format at the same time. Long responses are not automatically thorough, and a fixed limit forces suppliers to answer the question asked rather than to restate their catalog. Where a supplier exceeds the limit, the excess is usually the part that was not requested, and reading it is optional rather than necessary. Where a genuine technical annex is needed, number its pages and reference them from the main response so the reader can find the relevant drawing without searching. Accept a technical annex where drawings genuinely need space, but keep the main response short enough to be read by the whole evaluation group. Circulate the response template with the RFQ itself, so bidders know the shape of the answer before they decide how much to write.
Ask for the response in a single submission with a named contact and a stated validity period. Split submissions arriving over several weeks make it impossible to compare bids on the same information, and the bidder who submitted early is penalized for answering promptly. Confirm receipt to each bidder in writing, so nobody resends a duplicate package two days before the deadline and shifts the comparison onto two versions of the same offer. Keep the submitted packages in one folder with the receipt time recorded, because the version history of a bid is the first thing anyone asks about when the result is challenged.
Why put the pilot vehicle plan inside the RFQ?
A pilot is cheaper to negotiate before selection than after it. State the pilot vehicle you intend to use, who installs the equipment, how long it will run, what will be measured and what result would justify a wider order. Suppliers who understand the pilot plan quote the support it requires, and those who cannot support a pilot reveal that before you commit. Describe who pays for the pilot installation and any temporary equipment, because that small commercial detail decides whether the pilot starts on schedule or waits for a purchase order.
Name the pilot vehicle early enough that the supplier can check fitment against its drawings. A pilot arranged on a different cab variant from the one quoted tests the relationship rather than the product, and the resulting discussion is usually about blame rather than about cooling performance. If the exact vehicle is not yet available, say when it will be and ask for a provisional fitment review against the drawings in the meantime. Where no representative vehicle exists at all, consider renting or borrowing one for the pilot, because a test on the wrong cab answers a question nobody asked.
State what happens to the pilot unit afterwards. Will it stay in service, be returned, or be purchased at the sample price? An unresolved question about ownership at the end of a pilot can sour an otherwise successful evaluation, and it costs a sentence to settle at the beginning. Write the pilot schedule into the RFQ as well, with an intended start date and a review point, so that suppliers can plan support capacity instead of discovering the requirement after the order is placed. Add the name of the person who will sign off the pilot result, because a named decision maker turns a long evaluation into a scheduled review.
Include the acceptance criteria in the RFQ so that the pilot has a defined outcome rather than an impression. The criteria can be provisional at this stage, but their existence signals that the decision will rest on measurements agreed in advance, which tends to improve the quality of the technical proposals you receive. Keep the criteria short and observable, because a pilot judged against five clear measures produces a decision, while one judged against a general expectation produces a debate. Share the criteria with the bidder in advance as well, so that the proposal is written against the measures that will decide it.
Which RFQ mistakes are most common, and how are they corrected?
The most common mistake is asking for a price before describing the duty, which returns a product family rather than a proposal. The correction is a short application paragraph stating the vehicle, the overnight period, the ambient conditions and the required result, followed by the numbered requirements. Suppliers can work with an imperfect brief, but they cannot work with no brief at all. Correcting this one habit usually explains why an earlier tender returned offers that were difficult to compare at all.
The second mistake is leaving the installation boundary undefined, so each bidder assumes a different scope and the prices diverge for reasons unrelated to the equipment. State who supplies the mounting hardware, who performs the installation, who commissions the system and who provides the training, and require each bidder to confirm those responsibilities rather than infer them. A simple table with one row per responsibility and one column per bidder makes the differences obvious before the price comparison begins. Add one line asking who provides the circuit protection and cabling, because that single item accounts for a large share of post-award disagreements on installation scope. Ask for the mounting hardware as a priced item even if the supplier assumes the installer will fabricate it, so the comparison includes what the workshop would otherwise buy locally.
The third mistake is accepting documents that describe a product family instead of the exact model. Correct it by requiring the model code, the revision and the document version in the response, and by rejecting a bid that answers with general marketing material when a model-specific datasheet was requested. The rule is easy to apply and it filters out unprepared bidders quickly. Keep a short record of which bids were rejected for this reason, because a repeated pattern across tenders usually points to a gap in the brief rather than to a weak market.
The fourth mistake is treating the RFQ as a one-way document. Invite written questions to a single contact by a stated date, answer them to all bidders at once, and issue the answers as an addendum that forms part of the brief. Consistent answers keep the comparison fair, and the addendum record protects you if a bidder later claims it priced against a different understanding. Number the addenda and require bidders to confirm receipt, so the final comparison rests on one version of the brief that everyone can identify.
Next step
For a Vethy quotation, use the contact options on the Vethy website and include your vehicle, supply voltage, target market, required cooling period and installation constraints.
Sources and method
Original procurement or diagnostic guidance. This is a proposed method, not a report of a product test or a certification standard.
Frequently asked questions
What technical information does a supplier need to quote a parking AC correctly?
The supplier needs the vehicle make, model, year and cab type; photographs and dimensions of the intended mounting area; the electrical system with voltage, battery capacity and other engine-off loads; the required engine-off cooling period and the ambient conditions it must handle; and the installation constraints that apply. Add the destination market, because documentation and configuration options depend on it. With that set, a supplier can propose a configuration and state its assumptions instead of quoting a generic unit.
How detailed should vehicle information be in a parking AC RFQ?
Detailed enough that the supplier can check fitment on paper without asking a question. A dimensioned sketch of the roof or mounting area, one interior photograph and the battery location usually achieve that for a standard sleeper cab. Unusual bodies, roof equipment, raised roofs and vehicles with existing auxiliary systems need more, because those are where fitment problems actually occur. Send the extra detail for the difficult vehicles rather than padding the brief for every unit in a uniform fleet.
Why do suppliers return different configurations for the same RFQ?
Usually because the brief left the duty or the energy boundary open, so each supplier optimized against a different assumption about overnight duration, battery capacity or acceptable depth of discharge. Occasionally it is because one supplier proposed a different architecture, such as a rooftop against a split system, on fitment grounds. Compare the assumptions before comparing the products; once the assumptions are aligned, the remaining differences are usually genuine engineering choices that a pilot can settle.
When should a fleet buyer send an RFQ instead of ordering standard units?
Send an RFQ when the vehicle mix, duty cycle, installation arrangements or documentation requirements are not fully covered by a standard catalog unit, or when the order is large enough that configuration and support terms are worth negotiating. For a few identical vehicles with a known fitment, a standard unit with a confirmed datasheet may be sufficient. The deciding question is whether a supplier could plausibly deliver the wrong configuration without noticing, and the RFQ exists to make that unlikely.