For some products, there is little or no room for maneuver in pricing. Vendors buy HVAC components from manufacturers and may not have any way of getting them at a lower price. However, not all negotiations have to be about getting the lowest price per item. Discuss the quote with the HVAC contractor and ask if there is room for negotiation.
Be respectful and polite, but don't hesitate to ask for a better price. Some companies may be willing to negotiate to take over your business, especially if they compete with other companies for the position. Make sure you communicate your needs and budget clearly and see if there are areas where you can save some money. However, keep in mind that not all air conditioning companies will be willing to negotiate their prices, and you decide if their price is reasonable and fits your budget.
HVAC dealers get different price discounts from equipment manufacturers, so the best companies may also offer you better deals. If the HVAC contractor isn't willing to provide you with an all-inclusive quote, then it could be a warning sign that it's not a reliable company.